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: Medicine
Commonest cause of cerebral infarction is - 
Select and explain. 
A. Embolism, B. Arteritis, C. Thrombosis, D. Cysticercosis
A: Embolism
Answer: A: Embolism 
Explanation: None