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
Basilar insufficiency shows: 
Select and explain. 
A. Ptosis, B. Blurred vision, C. Diplopia, D. VI nerve weakness
A: Ptosis
Answer: A: Ptosis 
Explanation: Ans. Ptosis