This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2017, Subject name: Surgery
A patient undergoes surgery in pelvic region. Which vein is most likely to result in thrombosis? 
Select and explain. 
A. Iliac vein, B. Femoral vein, C. Calf vein, D. IVC
C: Calf vein
Answer: C: Calf vein 
Explanation: Risk factors for DVT Acquired: Obesity Infection Prolonged immobilization in surgery of lower limb or pelvic region M/C site of DVT - Calf vein or soleal vein M/C site of DVT leading to PE - Thigh vein or Femoropopliteal vein