This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of orbit, Lids and lacrimal apparatus, Subject name: Ophthalmology
Most common cause of ptosis 
Select and explain. 
A. Myasthenia gravis, B. Paralysis of 3rd nerve, C. Idiopathic, D. Congenital
D: Congenital
Answer: D: Congenital 
Explanation: *Congenital myogenic ptosis is the most common type of ptosis and is often bilateral. Ref: Clinical ophthalmology p.786