Answer: D) ensure that the verb tense remains the same across clauses.
Step-by-step explanation: parallelism or parallel structure is a literary device that consists in the repetition of the grammatical structure of different words or phrases in a sentence or paragraph, in order to emphasize an idea or to create an impact in the audience. When using proper parallel structure, we need to ensure that the verb tense remains the same across clauses, because this will help to mantain the grammatical structure in a sentence.