Answer: Option (b) is the correct answer.
Step-by-step explanation:
When it rains, then mud in the backyards become wet. It is known that earthworms live inside earth and diffusion of oxygen gets slower through water than through air.
As a result, supply of oxygen to the worms decreases in wet mud hence, they come to the surface in order to breathe.
Thus, we can conclude that wet mud in the backyard most likely formed the earthworms.