Which one of the following groups of animals reproduces only by sexual means?

Options

(a) Ctenophora
(b) Cnidaria
(c) Porifera
(d) Protozoa

Correct Answer:

Ctenophora

Explanation:

In Ctenophora, sexes are not separate. Reproduction takes place only by sexual means. In Cnidaria, which exist in both forms, polyps produce medusae asexually and medusae form the polyps sexually. Porifera (sponge) reproduce asexually by fragmentation and sexually by formation of gametes. Protozoans come under protista which reproduce asexually and sexually by cell fusion and zygote formation.