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
[{'content': 'Bernard soluier syndrome is due to defective \nSelect and explain. \nA. Platelet adhesion, B. Platelet aggregation, C. Platelet secretion, D. Platelet sequestration', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]