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
DMF index was given by: 
Select and explain. 
A. Mien, Palmar, Knutson and Henry in 1938, B. Moller in 1966, C. Gruebbel in 1994, D. Katz in 1980
A: Mien, Palmar, Knutson and Henry in 1938
Answer: A: Mien, Palmar, Knutson and Henry in 1938 
Explanation: None