This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular Motility, Subject name: Ophthalmology
Person is not able look down. WTiich extra ocular muscle is affected: 
Select and explain. 
A. Inferior oblique, B. Inferior rectus, C. Superior rectus, D. Lateral rectus
B: Inferior rectus
Answer: B: Inferior rectus 
Explanation: Ans. (b) Inferior rectusRef : A.K. Khurana 6th ed. / 337-39* The function of inferior rectus is depression of eyeball, which helps to see down.* Its yoke muscle is superior oblique, which also has the similar function as inferior rectus.