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: Gynaecology & Obstetrics
The serum tumor maker for trophoblastic tumor is : 
Select and explain. 
A. a HCG, B. Calcitonin, C. b HCG, D. g HCG
C: b HCG
Answer: C: b HCG 
Explanation: b HCG