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
Doppler USG in twins is used for: 
Select and explain. 
A. Twin to twin transfusion, B. Conjoined twin, C. Diagnosis of twins, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None