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: Microbiology
[{'content': 'Early sign of tetanus is locked jaw due to early involvement of: \nSelect and explain. \nA. Masseter, B. Medial pterygoid, C. Temporalis, D. Lateral pterygoid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Early sign– increased tone of\xa0masseter muscles\xa0called as\xa0trismus/lock\xa0jaw, followed by sequential involvement of nerves of head, trunk and extremities (Descending tetanus).', 'role': 'assistant'}]