The answer is indeed "Students like practical mathematics teachers."
Explanation:
A faulty or vague pronoun reference happens when a pronoun has two or more antecedents, and it is unclear to which antecedent it refers. Pronouns are words that substitute nouns in a sentence to avoid repetition. Writers should always be careful not to leave vague pronoun references behind since they can cause ambiguity in the text.
In the sentence "Students like mathematics teachers because they are practical," the third-person plural pronoun "they" has two antecedents, "students" and "teachers". It can, therefore, refer to any of them, which is the source of the sentence's ambiguity. We may assume that "because they are practical" refers to the teachers due to the common knowledge that people who work in the mathematics field are usually practical. Thus, to eliminate the vague reference, we can simply place the adjective "practical" before the noun it refers to:
Students like practical mathematics teachers.
