Which of the following statement(s) is/are correct regarding phylum coelenterata? (i) They are aquatic, mostly marine, sessile or free- swimming, radially symmetrical animals. (ii) They have a central gastro-vascular cavity with a single opening called hypostome. (iii) Digestion is extracellular and intracellular. (iv) Examples are Sycon, Spongilla and Euspongia.

• A. (i) and (ii)       
• B.        (i) and (iv)
• C. (i), (ii) and (iii)  
• D.        All of these