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': 'Amount of drug left after four plasma half–lives is: \nSelect and explain. \nA. 6.25%, B. 12.50%, C. 25%, D. 50%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]