The canal system is a characteristic feature of …………. (BHU 1999, 2002)
A. sponges
B. echinoderms
C. helminthes
D. coelenterates
Answer:A
The canal system is a characteristic feature of …………. (BHU 1999, 2002)
A. sponges B. echinoderms C. helminthes D. coelenterates