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: Pathology
[{'content': 'The main clinicalfeature of primary antiphospholipid syndrome is \nSelect and explain. \nA. Thrombosis, B. Vascular injury, C. Trauma, D. Bleeding disorder', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]