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 earliest diagnostic test of pregnancy : 
Select and explain. 
A. Ultrasound, B. Beta HCG, C. Fetal movements, D. Fetal hea sounds
B: Beta HCG
Answer: B: Beta HCG 
Explanation: Beta HCG