This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Aerial thrombosis is seen in \nSelect and explain. \nA. Homocysteinemia, B. Anti phospholipids syndrome, C. Protein s deficiency, D. Protein c deficiency', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref Harrison 18/e p462; 9/ep123', 'role': 'assistant'}]