This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small Intestine - Mesenteric Ischemia, Subject name: Surgery
Cause of acute mesenteric ischemia is- 
Select and explain. 
A. Embolus, B. Vasospasm, C. Thrombosis, D. Venous thrombosis
A: Embolus
Answer: A: Embolus 
Explanation: Ans. is 'a' i.e.. Embolus o Most common cause of acute mesentric ischemia is embolus to superior mesentric artery and rarely the iliac artery,o Source for embolus is usually heart most commonaly left atrial or ventricular thrombi or vascular lesions.