Characterize the Life Cycle of Cnidarians

Characterize the life cycle of cnidarians.

A) All species have both polyps and medusae.
B) Some have only polyps,some have both polyps and medusae,and others have medusae and a reduced polyp stage.
C) Some species have only medusae and others have both polyps and medusae.
D) Some species have only polyps and others have both polyps and medusae.
E) Some species have polyps and others have medusae,but no species has both.