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
Use of Doxycycline hyclate 20 mg. for a period of time forms 
Select and explain. 
A. Prophylactic antimicrobial therapy, B. Systemic antimicrobial therapy, C. Host modulation therapy, D. Local drug delivery
C: Host modulation therapy
Answer: C: Host modulation therapy 
Explanation: None