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: Anatomy
The posterior bellies of digastric muscle are especially active during 
Select and explain. 
A. Swallowing and speech, B. Swallowing and smiling, C. Swallowing and chewing, D. Swallowing and frowning
C: Swallowing and chewing
Answer: C: Swallowing and chewing 
Explanation: Digastric

Origin – The posterior bellay arises from the mastoid, or digastric, notch immediately behind the mastoid process of the temporal bone.
Insertion – The posterior belly passes downwards and forwards towards the hyoid bone where it becomes the intermediate digastric tendon and joints with the anterior belly.
Nerve supply – Derived from the digastric branch of the facial nerve.
Vasculature – Arterial blood supply from the posterior auricular and occipital arteries.
Action – The muscle depresses the mandible and can elevate the hyoid bone. The posterior bellies act in unison and are particularly active during swallowing and chewing.