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
Corneal dystrophies are 
Select and explain. 
A. Primary & unilateral, B. Primary & bilateral, C. Primary, bilateral with systemic disease, D. Primary, unilateral without systemic disease
B: Primary & bilateral
Answer: B: Primary & bilateral 
Explanation: B i.e. Primary & bilateral