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
Diameter of the Vossius's ring is: 
Select and explain. 
A. Equal to normal pupil, B. Smaller than the normal pupil, C. Slightly larger than the normal pupil, D. Much larger than the normal pupil
B: Smaller than the normal pupil
Answer: B: Smaller than the normal pupil 
Explanation: Ans. Smaller than the normal pupil