Question

a man observed an earthworm and saw a swollen region towards the anterior side of the earthworm a) what is this region called b) which segments constitute this swelling

Answer 1

a Prostomium

b. The 1st segment or the mouth constitutes this swelling.

Earthworm:

An earthworm is a tube-shaped, segmented worm found in the phylum Annelida. Earthworms are commonly found living in soil, feeding on live and dead organic matter. An earthworm's Its digestive system runs throughout the length of its body. It conducts respiration through its skin. It has a double transport system composed of coelomic fluid that moves within the fluid-filled coelom and a simple, closed blood circulatory system.