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
Which of the following gene defects is associated with development of medullary carcinoma of thyroid - 
Select and explain. 
A. Ret proto oncogene, B. FAP gene, C. Rb gene, D. BRCA 1 gene
A: Ret proto oncogene
Answer: A: Ret proto oncogene 
Explanation: None