This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Squint, Subject name: Ophthalmology
A patient is NOT able to look downward. Which muscle may be paralyzed? 
Select and explain. 
A. Superior oblique, B. Superior rectus, C. Inferior oblique, D. Lateral rectus
A: Superior oblique
Answer: A: Superior oblique 
Explanation: MUSCLES helping in looking down - Inferior rectus - primary function supplied by 3rd cranial nerve Superior oblique - secondary function-suppliecd by 4th cranial nerve