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: Pathology
[{'content': 'A shape of Birbeck granules is - \nSelect and explain. \nA. Hockeystick, B. Bat, C. Ball, D. Tennis racket', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Under the electron microscope, Birbeck granules have a pentalaminar, rod\xa0like, tubular appearance and\xa0sometimes a dilated terminal end resembling tennis-racket appearance.', 'role': 'assistant'}]