Select the most appropriate option to fill in the blank.
She was not only intelligent _______ also extremely humble.

Correct option is C

The correct option to fill in the blank is (C) but.

Explanation: This sentence uses the correlative conjunction pair 'not only... but also'. These conjunctions work together to join two related ideas or qualities of the same subject.

Example: He is not only a great singer but also a talented dancer.

Information Booster: Correlative conjunctions must always be used in their correct pairs: Neither...nor, Either...or, Not only...but also, Scarcely...when.

So the correct answer is (c)