The four regions of the earthworm are, A is the anterior end,B is the dorsal side, C is the posterior end, and D is the ventral side.
What are earthworms?
Earthworms are common soil dwellers who are both safe and useful. Earthworms help plants flourish by collapsing dead and decaying organic debris into rich humus soil.
They also aerate the soil and enhance flow by digging small canals and holes.
The four regions of the earthworm are;
A is the Anterior end
B is the Dorsal side
C is the Posterior end
D is the Ventral side
Hence all the regions are clearly defined with the help of digrame.
To learn more about the earthworms refer to the link;
https://brainly.com/question/20992190