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: Radiology
Deep vein thrombosis post-operatively is best diagnosed by 
Select and explain. 
A. USG, B. Ascending venography, C. X-ray, D. Clinically
B: Ascending venography
Answer: B: Ascending venography 
Explanation: Ascending venography