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 weakness of the levator palpebrae superioris innervated by third cranial nerve III occulomotor . Ref: Ak khurana 6th edition page no:378