Correct Answer: cheap

Solution : The correct choice is the first option.

The word expensive describes something that has a high cost. Cheap is used to describe something that has a low cost and is affordable. In the context of the sentence, it means that the outfit she was wearing was not expensive, indicating that it was affordable.

The meanings of the other options are as follows:

Precious means something of great value, often due to rarity, sentiment, or significance.

Premium means an additional cost or payment, often for better quality or special features.

Costly means involving a high expense or requiring a significant amount of money to acquire or maintain.

The other options are not appropriate antonyms of the given word.

Therefore, the correct sentence should be: "She was wearing a cheap new outfit."