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
[{'content': 'Bioavailability is- \nSelect and explain. \nA. Amount of drug that reach the systemic circulation, B. Drug metabolized in liver before the drug reaches the systemic circulation, C. Drug metabolized in liver after the drug reaches the systemic circulation, D. Maximum by rectral route', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Amount of drug that reach the systemic circulation", 'role': 'assistant'}]