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: Medicine
In a patient suffering from rheumatic heart disease who has to undergo dental treatment, when are prophylactic drugs given? (Or) A 40kg man with prosthetic heart, antibiotics are given for extraction of tooth how many hours before the procedure? 
Select and explain. 
A. 3 hrs. before operation, B. 7 days before operation, C. 1 hr. before operation, D. 1 day before operation
C: 1 hr. before operation
Answer: C: 1 hr. before operation 
Explanation: None