Can you please verify if I have done this correctly

1. Each advisor was contacted by his students.

my answer
Each advisor was contacted by their students.
or Each advisor was contacted by his or her students.

His or her students, not their students (because you are saying EACH advisor.)

Yes, your answer is correct. When referring to "each advisor," it is important to use a singular pronoun such as "his or her" instead of "their" because "their" is plural. This ensures agreement in number between the subject ("advisor") and the pronoun ("his or her"). So, the correct version would be "Each advisor was contacted by his or her students."