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
Early sign of tetanus is locked jaw due to early involvement of: 
Select and explain. 
A. Masseter, B. Medial pterygoid, C. Temporalis, D. Lateral pterygoid
A: Masseter
Answer: A: Masseter 
Explanation: Early sign– increased tone of masseter muscles called as trismus/lock jaw, followed by sequential involvement of nerves of head, trunk and extremities (Descending tetanus).