Help Please. What is wrong with sentence 4?
A.
A lot should be one word.
B.
There should be a comma after moist.
C.
It has should be they have.
D.
Nothing is wrong with the sentence.

(1) Pill bugs are commonly known as “roly polies.” (2) They are harmless yet interesting creatures. (3) Although they are considered insects, pill bugs are closely related to sea critters. (4) They have lungs that are a lot like gills, and because of this, it has to stay moist on land. (5) These bugs like cool, damp places, so land under a shady rock is a prime spot for them to call home. (6) Rocks also make great holmes for roly polies because they like tight spaces. (7) Pill bugs eat rotting plants for diner most of the time. (8) To protect themselfs against enemys, they roll into balls, which look like pills.