ExamEval
Item Writing Flaws
Number of Answer Choices

The Optimal Number of Answer Choices: 3, 4, or 5 for Multiple-Choice Questions

By Sean P. Kane, PharmD, BCPS

Published June 27, 2025

Three to Five Answer Choices is Best

The number of answer choices in a multiple-choice question directly affects both the fairness and the quality of an assessment. Having too few options increases the probability that a student will guess correctly. Writing too many answer choices takes longer for faculty and can overwhelm students when selecting the best answer. In both cases, having too few or too many answer choices reduces the accuracy of a question in assessing a student's knowledge.

Research in educational measurement consistently shows that three to five answer choices is the optimal range for most multiple-choice questions. This range strikes a balance between reducing the probability of guessing, maintaining question quality, and preserving the discrimination index of the question.

Critical Issue

The number of answer choices directly impacts the psychometric properties of a question. Too few options increase the likelihood of guessing correctly, while too many can be difficult to write and may not improve the question's quality. The key is to have a sufficient number of plausible distractors to effectively assess knowledge.

Two Answer Choices: High Guessing Probability

When a question has only two answer choices (e.g., true/false), the chance of guessing correctly is 50%. This is far too high for most assessments and allows students to score well without demonstrating real knowledge.

Three to Five Answer Choices: The Sweet Spot

Research by Schneid et al. (2014) and others has shown that three to five options is the ideal range for most multiple-choice questions. This range provides a good balance between reducing the chance of guessing and the difficulty of writing plausible distractors. Three-option questions are often just as effective as four- or five-option questions, and they are easier to write.

"Functioning" Distractor Answers

In the literature, a "functioning" distractor answer is defined as an incorrect answer that is selected by at least 5% of test-takers. Conversely, a non-functioning distractor is an answer choice that nearly no students (< 5%) select.

In health sciences education, exam questions have an average of 1.5 functioning distractor answers. In other words, a typical exam question has one or two incorrect answer choices that at least 5% of students select. For that reason, exam questions only need three answer choices for a high-quality multiple-choice assessment of knowledge. Additional answer choices tend to result in more non-functioning distractors that do not improve the performance of the question.

Example of Excessive Answer Choices in Health Sciences Education

Flawed Question

A 50-year-old man is started on lisinopril 10 mg PO daily for stage 1 hypertension. Which of the following laboratory values should be obtained in the next 1-2 weeks to assess for safety of this medication?

A. Serum sodium

B. Serum chloride

C. Serum potassium ✓

D. Serum bicarbonate

E. Serum glucose

F. Serum magnesium

G. Serum phosphate

H. Serum calcium

Although the answer choices are all common lab values, there is no value in providing eight answer choices instead of three to five answer choices. Most of these answers will be non-functional (selected by less than 5% of students).

Corrected Question

A. Serum sodium

B. Serum potassium ✓

C. Serum bicarbonate

D. Serum magnesium

The corrected question uses four answer choices, which is within the optimal range of three to five answer choices. A reduced number of answer choices is quicker to write for faculty, quicker to read for students, and results in less cognitive burden.

Quality Over Quantity

The most important factor in multiple-choice questions is the quality of the distractors, not the number of options. Three to five well-written, plausible distractors are much better than seven options where several are obviously incorrect.

Good distractors should:

Represent common misconceptions
Be plausible to students who haven't mastered the content
Require content knowledge to eliminate
Be similar in length and complexity

Many health professions educators struggle to identify when their exam questions contain too many or too few answer choices. ExamEval provides AI-powered analysis that automatically identifies optimal answer choice counts and other item-writing flaws, helping educators create more reliable assessments that better reflect student learning outcomes.

References

Tarrant M, Ware J, Mohammed AM. An assessment of functioning and non-functioning distractors in multiple-choice questions: a descriptive analysis. BMC Med Educ. 2009;9:40. Published 2009 Jul 7. doi:10.1186/1472-6920-9-40
Tarrant M, Ware J. A comparison of the psychometric properties of three- and four-option multiple-choice questions in nursing assessments. Nurse Educ Today. 2010;30(6):539-543. doi:10.1016/j.nedt.2009.11.002
Redmond SP, Hartigan-Rogers JA, Cobbett S. High time for a change: psychometric analysis of multiple-choice questions in nursing. Int J Nurs Educ Scholarsh. 2012;9:/j/ijnes.2012.9.issue-1/1548-923X.2487/1548-923X.2487.xml. Published 2012 Nov 26. doi:10.1515/1548-923X.2487
Schneid SD, Armour C, Park YS, Yudkowsky R, Bordage G. Reducing the number of options on multiple-choice questions: response time, psychometrics and standard setting. Med Educ. 2014;48(10):1020-1027. doi:10.1111/medu.12525