Which one of the following statements about all the four of Spongilla, leech, dophin and penguin is correct ?
A. Penguin is homoiothermic while the remaining three are poikilothermic
B. Leech is fresh water form while all others are marine
C. Spongilla has special collared cells called choanocytes, not found in the remaining three
D. All are bilaterally symmetrical
