This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Targeted Anticancer Drugs and Immunosuppressants, Subject name: Pharmacology
[{'content': 'Monoclonal antibody used in Head and neck cancer is:- \nSelect and explain. \nA. Pembrolizumab, B. Trastuzumab, C. Rituximab, D. Ocralizumab', 'role': 'user'}, {'content': "Answer: A \nExplanation: Drug Mechanism of action Uses Pembrolizumab Monoclonal antibody against PD 1 * Multiple myeloma * Non small cell lung cancer * Head and neck cancer * Any cancer containing mismatch repair Trastuzumab Monoclonal antibody against her-2/neu Breast cancer, gastroesophageal junction cancer Rituximab Monoclonal antibody against CD20 Non hodgkin's lymphoma(NHL), chronic lymphocytic leukemia(CLL) Ocrelizumab Monoclonal antibody against CD20 Primary progressive multiple sclerosis(PPMS)", 'role': 'assistant'}]