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: Dental
The six keys to normal occlusion were given by: 
Select and explain. 
A. Lawrence F. A., B. Angle, C. Lischer, D. Moyer
A: Lawrence F. A.
Answer: A: Lawrence F. A. 
Explanation: ANDREWS SIX KEYS TO NORMAL OCCLUSION
Lawrence F Andrews studied 120 casts of non-orthodontic patients with normal occlusion for four years (1960-1964). He identified 6 key characteristics.
He was of the opinion, that for normal occlusion to exist these six characteristics had to be present. According to Andrews, the 6 keys to normal occlusion contributed individually and collectively to the total scheme of occlusion and, were therefore essential for an orthodontic treatment to be considered successful.
Ref: Textbook of orthodontics Gurkeerat Singh 2nd ed page no 59