[A] : Sponges are primitive multicellular animals that probably evolved a multicellular structure independently of other animals .
[R] : Sponges are stationary animals and remain fixed to substratum while water passes over them .
A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false
