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
Only nerve that originates from the dorsal surface of the brain stem is 
Select and explain. 
A. Trochlear, B. Occulomotor, C. Vagus, D. Abducent
A: Trochlear
Answer: A: Trochlear 
Explanation: None