The correct option is D While the cops were busy munching on donuts
An adjunct is a word, phrase or clause that can be eliminated from the
sentence, without affecting it grammatically. The sentence would still
make sense without an adjunct. Adjuncts are usually adverbs, adverb
phrases or adverb clauses. The clause in option A is an adverb clause of time, without which the sentence is still complete in meaning (being an independent clause). Hence option A is the adjunct. "The thief" is a subject, "took" is a verb and "took the chance and fled" is a compound verb, containing two actions. Without the subject and verb, a sentence is not complete, hence options B, C and D are incorrect.