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: Physiology
[{'content': 'Protein filtration across cerebral capillaries is limited by: \nSelect and explain. \nA. Fibrous tissue, B. Foot process of astrocytes, C. Low BP, D. High CSF pressure', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Foot process of astrocytes Blood Brain Barrier (BBB)', 'role': 'assistant'}]