There are people violating freedom of speech, but it's hard to sue them. Which phrase can be deleted before rewriting the sentence?

What word or phrase is modified by the prepositional phrase in the sentence below? marisol's puppy likes napping under the couch because it is warm and cozy

Can someone me with this english question

Plz ! i genetic mutation occurs in a rabbits muscle cell this genetic mutation will be passed on to, a. the existing cells in the rabbits body. b. the cells that are next to the mutant muscle cell. c. cells that are produced when the mutant cell divides. d. the cells of the rabbits offspring.