This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
[{'content': 'Effectiveness of blood brain barrier is by \nSelect and explain. \nA. Thick basement membrane, B. Tight arrangement of astrocytes, C. Tight endothelial function, D. Microglial cell', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The blood-brain barrier is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane. Ref: guyton and hall textbook of medical physiology 12 edition page number:671,672,673', 'role': 'assistant'}]