This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Which of the following statements best applies to the following diagram? \nSelect and explain. \nA. Depicts the cell-membrane MHC product associated with narcolepsy, B. Essential for the transplacental passage of antibody, C. Found on T and B lymphocytes and all nucleated cells, D. Present on macrophages but not neutrophils', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The figure shown in the question is a schematic representation of the MHC class I molecule, which has a CD8 binding site (a3 ) and a peptide-binding site (a1 and a2 ). MHC class I is active on all nucleated cells.', 'role': 'assistant'}]