Effect of Option Number on Psychometric Quality of Single-answer MCQs in Medical Exams

Introduction: Multiple choice questions (MCQs) allow efficient student assessment and broader content coverage in less time. However, crafting clear stems and plausible options is challenging and time-consuming. Despite research supporting three-option MCQs, many medical educators continue using four or five options due to limited evidence from undergraduate medical settings. Therefore, this study aimed to compare the quality indices of MCQs with 3, 4, and 5 options through item analysis and to determine the optimal number of options for effective assessment. 
Methods: The study included 107 first-year and 91 second-year MBBS students. Tests were conducted two weeks after internal assessments. Students were randomly divided into three groups: first year (36, 35, 36) and second year (29, 31, 31). Three sets of 30 biochemistry MCQs were used, each with 3, 4, or 5 options for years. For every item, the Difficulty Index (DIF I), Discrimination Index (DI), and Distractor Effectiveness (DE) were analyzed. 
Results: In 1st year MBBS, 3-option MCQs were easiest (DIF I 69.28%) with highest distractor effectiveness (83.33%) and moderate discrimination (0.27). Four-option MCQs showed the highest discrimination (0.30) but lower distractor effectiveness (69.96%). Five-option MCQs were hardest (DIF I 57.36%) but had lowest discrimination (0.21) and distractor effectiveness (64.16%). In 2nd year, 3-option MCQs had highest difficulty (53.66%) and discrimination (0.32), while 4-option MCQs had best distractor effectiveness (86.64%). Non-functional distractors increased with more options. 
Conclusion: Reducing MCQ options in Biochemistry to three improves ease and distractor functionality without compromising discrimination, making them a more efficient and effective choice for assessment design.