The sentence “Carl, you both lie and act like a terrific monster!" my little brother declared” does not use parallel structure correctly.
Parallel structure (also called parallelism) is the repetition of a chosen grammatical form within a sentence. By making each compared item or idea in your sentence follow the same grammatical pattern, you create a parallel construction.
The correct answer between all the choices given is the second choice or letter B. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.