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: Unknown
Best for unruptured ectopic pregnancy is - 
Select and explain. 
A. Per abdominal US, B. HCG, C. Trans vaginal USG, D. Amniocentesis
C: Trans vaginal USG
Answer: C: Trans vaginal USG 
Explanation: Ans-C