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: Social & Preventive Medicine
[{'content': 'Which of the following means of contraception is the best method to achieve Net Reproductive Rate (NRR)=1? \nSelect and explain. \nA. IUCD, B. Condoms, C. Vasectomy, D. Oral pills', 'role': 'user'}, {'content': 'Answer: C \nExplanation: NRR is the most significant indicator of feility. Sterilization accounts for 80% of effective couple protection and hence is the best method among the above choices.', 'role': 'assistant'}]