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
Only cataract which is reversible on treatment 
Select and explain. 
A. Diabetic cataract, B. Oil drop cataract, C. Chalcosis, D. Shield cataract
B: Oil drop cataract
Answer: B: Oil drop cataract 
Explanation: Only cataract which is preventable/reversible on treatment Oil drop cataract.