The answer is: "jacket and tie"
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The other answer choices:
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"package of ties";
"dress suit";
"sweater and skirt set";
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all agree with the verb in the sentence given; because that are in a 'set' or come in a "single unit" and function as a "single noun";
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The phrase: "jacket and tie" are not "grouped together" (e.g. in a "single set or kit") and should take the "plural" form of the verb.
