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: Surgery
[{'content': 'The deficiency of all of the following factors increases the incidence of thrombus formation except - \nSelect and explain. \nA. Lipoprotein A, B. Protein - C, C. Anti - thrombin III, D. Protein - S', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]