Final answer:
Segmentation is the process of breaking down food into smaller pieces in the small intestine.
Step-by-step explanation:
Segmentation is the process of breaking down food into smaller pieces in the small intestine. It helps in mixing the food with digestive enzymes and increasing the surface area for absorption. Ingestion (a) refers to the intake of food, propulsion (b) refers to the movement of food through the digestive tract, and absorption (d) refers to the uptake of nutrients into the bloodstream.