Final answer:
The correct answer to the student's question regarding the site of digestion in sponges is A. amoebocytes. Digestion in sponges happens intracellularly within specialized cells called amoebocytes, which distribute nutrients throughout the sponge after initial food particle capture by choanocytes.
Step-by-step explanation:
Unlike more complex animals, sponges lack a true digestive system. Instead, they rely on specialized cells known as choanocytes to initially trap food particles through a process called phagocytosis as water passes through them.
After the choanocytes ingest the food particles, amoebocytes then distribute the nutrients to other cells throughout the sponge by further intracellular digestion, effectively serving the sponge's requirements for digestion and nutrient distribution. This entire process happens within individual cells rather than in a designated digestive cavity or tract.