Development is indirect in which of the following the phyla?
(a) Platyhelminthes
(b) Ctenophora
(c) Cnidaria
(d) Porifera
Only (a) and (b)
Only (c) and (d)
Only (a), (b) and (c)
(a), (b), (c) and (d)
Indirect development is observed in the phyla Platyhelminthes, Ctenophora, Cnidaria and Porifera.