The correct answer is: A. great
The other options are:
- B. fantastic: This word is too strong to describe someone who looks good in a new dress.
- C. silly: This word is not appropriate to describe someone who looks good in a new dress.
- D. splendid: This word is too formal to describe someone who looks good in a new dress.
The word "great" is the most appropriate word to describe someone who looks good in a new dress. It is a positive word that conveys the idea that the person looks attractive and stylish.
