A sponge actually feeds by a. acting as a net in a current that sweeps food particles through it.
b. squeezing the spongocoel cavity and sucking debris in and out through the osculum.
c. the beating of the flagella of collar cells, forming a current; food is absorbed by collar cells.
d. the beating collar cells form a current from osculum to pores; the food is engulfed by amoebocytes in the central cavity of the sponge.
e. water the moves gently through the sponge and the amoebocytes that engulf passing food.

c. the beating of the flagella of collar cells, forming a current; food is absorbed by collar cells.

Explanation:

Sponges contains the unique feeding system that should be with the animals. Rather of mouths they have the tiny pores that we called as the ostia displayed on the outer walls via water is drawn. Here cells in the sponge walls strainer the food from the water because the water is pumped via the body and the little mouth

So as per the given options, the option c is correct as the collar cells would create the current and the food should be absorbed by the collar cells

thinking it would be physical characteristics