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': 'Researches decided to study the impact of iodized salt programme especially in hilly areas of Pakistan. They had chosen the most sensitive indicator for monitoring environmental iodine deficiency which was \nSelect and explain. \nA. Prevalence of goiter, B. Prevalence of neonatal hypothyroidism, C. Prevalence of myxedema, D. Urinary iodine excretion', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]