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: Pathology
In which of the following is medullary thyroid cancer is the most aggressive form - 
Select and explain. 
A. MEN type I, B. MEN type II a, C. MEN type II b, D. Sporadic cases
C: MEN type II b
Answer: C: MEN type II b 
Explanation: Medullary thyroid carcinoma in MEN 2B develops earlier and is more aggressive than in MEN 2A.