Which sentence is the best example of parallelism?

Which sentence is the best example of parallelism?

A. The house is as big as a castle and as spacious as an openprairie.

B. “Hand me one of those candles!” the groundskeeper yelled.

C. The car fought me for a bit before settling into a calm purr.

D. Do yourself a favor by doing your best and doing your duty.

Answer: Do yourself a favor by doing your best and doing your duty.

Parallelism is the use of same grammatical structure for words, phrases, or clauses in a sentence in order to create rhythm, clarity, and balance. In D, ‘doing your best’ and ‘doing your duty’ have parallelism; those are using the same structure of a repeated gerund phrase. These two clauses are also complementary both grammatically and semantically. The options A, B and C fail to show the same pattern. Option A uses a simile vs. metaphor, Option B, is dialogue and lastly(C) contrasts verbs . The parallelism between the two gerund constructions is the chief characteristic in D to show it as a good structural parallel sentence. The repetition results in a fluid, rhythmic sentence.