This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
In primary angle-closure glaucoma pilocarpine lowers the intraocular pressure by its direct action on the: 
Select and explain. 
A. Sphincter pupillae muscle, B. Ciliary epithelium, C. Trabecular meshwork, D. All of the above
A: Sphincter pupillae muscle
Answer: A: Sphincter pupillae muscle 
Explanation: Ans. Sphincter pupillae muscle