The policemen became suspicious as the hoodlums … in their office?

Analyze the question: The sentence needs a verb (past tense) that fits "in their office." The options differ in spelling (one "t" or two) and whether "about" is included.

Concept: "Ferret" is a verb meaning to search or rummage for something. The phrasal verb is "ferret about/around", meaning to rummage or search in a place.

Spelling rule: when adding -ed to a verb, we double the final consonant only if the stress is on the last syllable (e.g., refer → referred, prefer → preferred). "Ferret" is stressed on the first syllable (FER-ret), so the final "t" is not doubled. The correct past tense is ferreted, not "ferretted."

Solution:

• Option B and D use "ferretted," which is incorrect spelling. Eliminate them.
• Option A, "ferreted," is spelled correctly. However, "The hoodlums ferreted in their office" sounds incomplete, because the verb needs the particle "about" (or "around") to give the sense of rummaging.
• Option C, "ferreted about," gives: The policemen became suspicious as the hoodlums ferreted about in their office. This is correct and natural.

Answer: C. ferreted about

Tip: For verbs ending in a single consonant after a vowel, double the consonant only if the stress falls on the last syllable (admit → admitted, offer → offered, ferret → ferreted). Also, learn "ferret" with its particles: ferret about, ferret around, ferret out.