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: Pharmacology
Drug binds to activate the receptor in same fashion, which directly or indirectly brings effect, is: 
Select and explain. 
A. Inverse agonist, B. Antagonist, C. Agonist, D. Partial agonist
C: Agonist
Answer: C: Agonist 
Explanation: None