The sentence is not grammatically correct, it should be, "Last summer, Jim mowed one lawn, now he mows three." Mowed just one lawn doesn't make sense in one sentence.
I would say that the parallel list here is C) a lost puppy, a colored poster, and a happy boy.
This is because all words have an article <em>a, </em>and an adjective in front of them, so they are parallel.
B is the answer i chose because i thinks it best fits the question
She matures by
1. During the beginning she hates Peter and then towards the end she loves him
2. She begins to respect her mother towards the end.
3. She doesn't have dreams of being famous towards the end she wants to be a writer.
Hope this helps! Have a great day!