Answer: B. collar cells and amoebocytes
The collar cells have a funnel like collar and a flagellum. Collar cells whip their flagella to make water go through the sponge. Then the water brings nutrients and oxygen, while while also taking out waste and carbon dioxide.
Amoebocytes first deliver nutrients from choanocytes to the other cells, giving rise to eggs. Then they bring phagocytized sperm from choanocytes to eggs.
