Question

She is not only beautiful, ____________ smart.

Short answer

The best coordinating conjunction to correctly complete the sentence is 'but'. So, the complete sentence is: 'She is not only beautiful, but smart.'

Step-by-step solution

Identifying the conjunction type

In this sentence, we need a word that can join two independent clauses or phrases such that each gives a contrasting quality of the person involved. This is a classic case where a coordinating conjunction is employed.

Recognizing the contextual clues

The sentence begins with 'She is not only beautiful,' implying the following clause would provide more complementary information.

Filling in the coordinating conjunction

Considering the meaning and intentions of the sentence, the most appropriate conjunction to fill in the blank is 'but'. 'But' in the English language is used to introduce something contrasting with what has already been mentioned.