This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Nutritional Deficiencies, Subject name: Social & Preventive Medicine
[{'content': "The most sensitive indicator of 'Environmental iodine deficiency' is:- \nSelect and explain. \nA. Serum T4 levels, B. Serum T3 levels, C. Urine iodine excretion, D. Neonatal hypothyroidism", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Neonatal hypothyroidism is the most sensitive indicator of environmental iodine deficiency. Other useful indicators for assessment of Iodine deficiency: Prevalence of goiter Prevalence of cretinism Urinary iodine excretion (Major impact indicator) Measurement of thyroid function by determination of serum T4, TSH.', 'role': 'assistant'}]