This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'Following injury to a blood vessel, immediate haemostasis is achieved by- \nSelect and explain. \nA. Fibrin deposition, B. Vasoconstriction, C. Platelet adhesion, D. Thrombosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Robbins basic pathology, 9th edition, page no:79 Vascular injury primarily causes a transient aeriolar vasoconstriction through reflex neurogenic mechanisms augmented by local secretion of endothelin. All other options follow this. So the answer is option 2.', 'role': 'assistant'}]