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
Subantimicrobial dose of doxycycline is 
Select and explain. 
A. 20 mg doxycycline, B. 60 mg doxycycline, C. 80 mg doxycycline, D. 150 mg doxycycline
A: 20 mg doxycycline
Answer: A: 20 mg doxycycline 
Explanation: None