pronoun antecedents underline each one that's correct. every student must have his or her pencils

Answer 1

The correct pronoun antecedent in the sentence is "every student," which is singular and therefore requires a singular pronoun.

Here's the sentence with the correct pronoun underlined:

Every student must have his or her pencils.

(Note that "his or her" is correct here; however, consider using "their" in informal contexts, as it is increasingly accepted as a singular gender-neutral pronoun.)