This question consists of a sentence which is divided into

Solution

When using the phrase "one of the", the noun that follows should always be plural. This is because "one of the" refers to a selection or group of multiple items or people, so the noun must be in the plural form, even though the subject "one" is singular.

So, the error lies in part (2). The phrase "talented dancer" is incorrect because the subject "She" is singular, and the word "one" suggests that the noun following it should be in plural form to agree with the expression "one of the most." The correct phrase should be "talented dancers" (plural). The corrected sentence is:

"She is one of the most talented dancers in the entire troupe and performs effortlessly."