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: Anatomy
Ptosis may occur due to damage to: 
Select and explain. 
A. Trochlear nerve, B. Oculomotor, C. Trigeminal nerve, D. Superior oblique muscle
B: Oculomotor
Answer: B: Oculomotor 
Explanation: Ptosis is the drooping eyelid, may be seen in some clinical cases.
Oculomotor ptosis due to paralysis of the levator palpebrae (e.g., transtentorial herniation). 
Oculosympathetic ptosis due to paralysis of the superior tarsal (Muller) muscle as seen in Horner syndrome. This is a very slight ptosis, or pseudoptosis (e.g., Pancoast tumor).