Q.Sexually, earthworms are

Step 1. Earthworms are hermaphrodites (monoecious animals): each individual has both male reproductive organs (testes) and female reproductive organs (ovaries) in the same body.

Step 2. Despite carrying both sexes, an individual earthworm does not fertilize its own eggs, because the two sets of organs mature at different times - the sperm develops earlier than the ova, a timing difference called protandry.

Step 3. Because of this timing mismatch, two worms must mate and exchange sperm mutually, so fertilization is always cross-fertilization between two individuals, even though both are hermaphrodites.

Step 4. Option (a) is wrong because sexes are not separate; option (c) is wrong because self-fertilization is specifically avoided; option (d) is wrong because earthworms are not parthenogenic (they do not develop from unfertilized eggs).

Recall that hermaphroditism plus protandry (sperm maturing before eggs) is what forces cross-fertilization in earthworms.

• Assuming that being hermaphroditic automatically means an earthworm can self-fertilize.
• Confusing protandry (a timing difference between sperm and egg maturation) with parthenogenesis (development without fertilization at all).