Which segments of the earthworm are responsible for the formation of the cocoon?

For earthworms,identify the $(i)$ Class,$(ii)$ Genus,$(iii)$ Order,and $(iv)$ Family.

State the location of caeca in Earthworm and Cockroach.

Following are the statements about the prostomium of an earthworm.
$(a)$ It serves as a covering for the mouth.
$(b)$ It helps to open cracks in the soil into which it can crawl.
$(c)$ It is one of the sensory structures.
$(d)$ It is the first body segment.
Choose the correct answer from the options given below.

The approximate number of earthworms found in $1$ acre of land is..........

Earthworms possess which blood pigment?