In which segments of the earthworm are the septa absent?

Identify the incorrect statements among the following:
$(a)$ In earthworm,a single male genital pore is present.
$(b)$ Setae help in locomotion of earthworm.
$(c)$ The muscular layer in the body wall of earthworm is made up of only circular muscles.
$(d)$ Typhlosole is a part of the intestine of earthworm.

One direct use of earthworms to farmers is:

Which statement is incorrect for earthworm?

The most important use of $Pheretima \text{ } posthuma$ is:

One very special feature in the earthworm $(Pheretima)$ is that