To put the sentence in formal style, which revision is best?

• A. changing 'undertake' to 'go for'
• B. changing 'it's' to 'it is'
• C. changing 'investigate' to 'check out'
• D. changing 'job' to 'gig'

Answer: (B)

Formality in writing relies on avoiding contractions and using precise, standard forms. Expanding "it's" to "it is" removes the casual tone of the contraction, aligning the sentence with formal style. The other options would push the wording toward a more informal or slangy register: "go for" is casual compared with "undertake," "check out" is colloquial, and "gig" is informal slang for a job. So the best revision to achieve a formal tone is to use "it is" instead of "it's."