The sentence 'Big wave surfing is supposed to be both tremendously thrilling and an extraordinary danger.' is wrong because the tense and form of the first modifier "tremendously thrilling" is different from "extraordinary danger" and thus the sentence is not parallel because they do not follow the same form.
Answer: D) Big wave surfing is supposed to be both tremendously thrilling and an extraordinary danger.
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. From the given options, the sentence that is not parallel, is the corresponding to option D, because the structures "tremendously thrilling" and "extraordinary danger" are not similar.
The excerpt from Robert Burns' "To a Mouse" which best conveys understanding and forgiveness is" <span>An’ weary winter comin’ fast,/An cozie here, beneath the blast…</span>
