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
Skin of the entire upper lip is supplied by: 
Select and explain. 
A. Maxillary nerve., B. Facial nerve., C. Mandibular nerve., D. None.
A: Maxillary nerve.
Answer: A: Maxillary nerve. 
Explanation: None