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
The principle of the stenopaeic slit test is based on: 
Select and explain. 
A. Astigmatic fan, B. The circle of least diffusion, C. Pin-hole phenomenon, D. Sturm's conoid
C: Pin-hole phenomenon
Answer: C: Pin-hole phenomenon 
Explanation: Ans. Pin-hole phenomenon