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
The philtrum of the upper lip is formed largely by the: 
Select and explain. 
A. Lateral nasal process, B. Frontonasal process, C. Maxillary process, D. Mandibular process
B: Frontonasal process
Answer: B: Frontonasal process 
Explanation: None