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: Surgery
False about medullary Cancer thyroid is? 
Select and explain. 
A. Tumor marker is calcitonin, B. From parafollicular cells, C. RET mutation, D. 90% familial
D: 90% familial
Answer: D: 90% familial 
Explanation: 90% of medullary carcinoma thyroid is sporadic.