Final answer:
Occlusion is the term for the relationship between the maxillary and mandibular teeth when the jaws are closed, and the action of the masseter muscle is chewing.
Step-by-step explanation:
The relationship between the maxillary and mandibular teeth when the jaws are in a fully closed position is known as occlusion. This term refers to the contact between teeth and is an important aspect of dental health, ensuring that the forces of biting and chewing are properly distributed among all the teeth.
Regarding the action of the masseter muscle, the correct answer is (b) chewing. The masseter is one of the muscles that plays a major role in the process of mastication, which involves biting and grinding food in preparation for swallowing.