Final answer:
Choanocytes in sponges are responsible for creating water currents for water filtration, trapping and ingesting food particles for nutrient absorption, removing wastes, participating in reproduction by differentiating into sperm, and aiding in spicule formation for structural support. The correct option is A.
Step-by-step explanation:
The function of choanocytes involves water filtration, nutrient absorption, waste removal, and reproduction. These collar cells create water currents through the sponge, entrap microscopic food particles, and ingest them by phagocytosis.
They are also capable of differentiating into sperm cells for sexual reproduction. Apart from these functions, choanocytes are involved in spicule formation, where they support the structural integrity of the sponge alongside other specialized cells in the mesohyl.
Thus, the correct answer which explains the functions of choanocytes is: (A) Water filtration, nutrient absorption, waste removal, reproduction, spicule formation.