Answer:
"The program was written by Sara, who is an expert in her field."
"To whom should I talk to about the report?"
Step-by-step explanation:
Who is a pronoun that represents the subject of a sentence:
- Who would like to go to the supermarket?
- Who built that castle?
Whom is a pronoun that represents the object of either a verb or a preposition:
- To whom was the song dedicated?
- Whom do you trust?
- I am not sure with whom I will go to the concert.
By replacing the pronoun with he/she or him/her it is easier to realize its function:
Who/whom took my laptop?
He took my laptop (RIGHT) - him took my laptop (wrong)
So in this case, the correct pronoun to use is who.
Who/whom should I talk to about the issue with my boss?
I should talk to he (wrong) - I should talk to him. (RIGHT)
Here, the correct pronoun to use is whom.