Assertion (A): Animals belongimg to phylum Porifera are often called sponges.
Reason(R): The animals have porous bodies.

Options

A. Both A and R are true and R is the correct explanation for A.
B. Both A and R are true but R is not the correct explanation for A.
C. A is true and R is false.
D. A is false and R is true.

Explanation

Organisms belonging to phylum porifera are the organisms with a low degree of individuality and cellular organization. They appear plant like and their body bears several pores hence they are called porifera or sponges. These pores form a part of canal system through which water enters the body and several processes like nutrition, respiration, circulation and excretion is done at its simplest level through this system.
Hence, the correct option is (a).