What punctuation error is found in the sentence regarding Anita's ambitions: "Anita was a multi-talented student, who couldn't decide whether she wanted to be an astronaut; a veterinarian; or a professor"?

The correct choice highlights the misuse of semicolons in the sentence. Semicolons are primarily used to connect closely related independent clauses or to separate items in a complex list where commas are already utilized. In this case, the semicolon is incorrectly used to separate "an astronaut," "a veterinarian," and "a professor," which are not independent clauses, but rather parts of a single list.

A more appropriate choice for separating items in this list would be commas. By replacing the semicolons with commas, the sentence would accurately reflect the intention of listing Anita’s varied ambitions without creating unnecessary confusion. Thus, the error lies in the incorrect application of punctuation that does not conform to its grammatical rules.