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: Dental
Which of the muscles show least EMG activity, when mandible is in centric relation? 
Select and explain. 
A. Posterior fibres of temporalis, B. Middle fibres of temporalis, C. Medial pterygoid muscle, D. Lateral pterygoid muscle
D: Lateral pterygoid muscle
Answer: D: Lateral pterygoid muscle 
Explanation: The anatomic attachments of posterior and middle parts of temporalis, masseter and medial pterygoid muscle are actively involved in holding mandible in its centric relation. Most relaxed muscle out of given options is lateral pterygoid muscle and hence it will show least EMG activity.