This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pharmacology, Subject name: Pharmacology
[{'content': 'According to the two-state receptor theory, which of the following statements BEST explain the term "agonists"? They have \nSelect and explain. \nA. Strong affinity for receptor in active state (Ra), B. Strong affinity for receptor in inactive state (Ri), C. Equal affinity for Ra and Ri, D. Slightly more affinity for Ra than Ri', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In to state receptor theory, agonists and inverse agonists are thought to have a selective binding affinity for the pre-existing resting and active states', 'role': 'assistant'}]