Which of the following is a member of phylum $Porifera$?

Which phylum is characterized by a body with an internal cavity lined by food-filtering flagellated cells (choanocytes) and indirect development?

Assertion $(A):$ The body of sponges is supported by a skeleton.
Reason $(R):$ The skeleton of sponges is made up of spicules and spongin fibres.

State the location and function of the following:
$(i)$ Contractile vacuole
$(ii)$ Ostia

What type of symmetry is exhibited by the body of poriferans?

Assertion : Sponges belong to Porifera.
Reason : Sponges have a canal system.