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
Which of the following is used as surrogate for endogenous LH surge in IVF 
Select and explain. 
A. IGF, B. GnRH, C. HCG, D. hmg
C: HCG
Answer: C: HCG 
Explanation: HCG is used as surrogate for endogeneous LH surge in invitro fertilization.