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: Surgery
Vascular inflow occlusion of the liver is by - 
Select and explain. 
A. Clamping the hepatic artery, B. Occluding the portal vein, C. Clamping the hepatic veins, D. The Pringle manoeuvre
D: The Pringle manoeuvre
Answer: D: The Pringle manoeuvre 
Explanation: • Total clamping of the hepatic pedicle, by placing an atraumatic clamp across the foramen of Winslow.
• Appropriate-sized vascular clamp or loop snare easily controls hemorrhage from either the portal vein or the hepatic arteries.
• Inflow occlusion durations of up to 30 minutes can be tolerated safely in cirrhotic livers and possibly up to 60 minutes in early disease.
• If prolonged occlusion is required, intermittent clamping can be used with repeated clampings of 10-20 minutes duration, each followed by 5 minutes declamping.