In earthworms,respiration occurs through $...............$.

Select the incorrect option regarding the nervous system in an earthworm.

If a transverse section of $Pheretima$ is cut through the $20^{th}$ segment,it contains:

Answer in one word or one line.
How many spermathecae are found in earthworm?

What is the function of the typhlosole in an earthworm?

Choose the correct option for the following statements:
$(i)$ Earthworms have $4$ pairs of lateral hearts.
$(ii)$ The excretory organs of earthworms are nephridia.