This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Musculoskeletal system, Subject name: Anatomy
[{'content': 'Calcitonin is a marker of thyroid \nSelect and explain. \nA. Papillary carcinoma, B. Medullary carcinoma, C. Anaplstic carcinoma, D. Adenocarcinoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Refer Robbins page no Pg 1030 Medullary Thyroid Carcinomas. Familial medullary thyroid carcinomas occur in multiple endocrine neoplasia type 2 (MEN-2, see later) and are associated with germline RET mutations that lead to constitutive activation of the recep- tor. RET mutations are also seen in approximately one half of nonfamilial (sporadic) medullary thyroid cancers. Chromosomal rearrangements involving RET, such as the RET/PTC translocations repoed in papillary cancers, are not seen in medullary carcinomas.', 'role': 'assistant'}]