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': 'The term physical half–life is applicable to: \nSelect and explain. \nA. Repository preparations, B. Prodrugs, C. Radioactive isotopes, D. Alkylating agents', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]