Final answer:
The digestive diverticulum is the structure that projects into a bivalve's stomach to aid in digestion by keeping contents moving, releasing enzymes, and processing food.
Step-by-step explanation:
c. Digestive Diverticulum. The digestive diverticulum projects into a bivalve's stomach to provide continuous movement of the stomach contents, release digestive enzymes, and to help roll and churn the mucous-laden food mass.
Bivalves, such as clams and oysters, are a group of mollusks that do not possess a radula. Instead, they are equipped with specialized gills known as ctenidia, which they use for filter feeding.
The mantle is an important tissue in mollusks that secrete the shell—but in bivalves, it also plays a role in the formation of the mantle cavity necessary for their feeding process. Unlike other mollusks, bivalves' intake of food and subsequent digestion rely on the movement and process of the ctenidium structure, combined with the action of the digestive diverticulum in their unique digestive systems.