The correct choice to fill the blank is: That.
So, we will have;
Who was that man you talked to yesterday?
'That' can function as a pronoun, a determiner, and an adverb.
In this sentence provided above, 'that' functions as a determiner. It was used to reference the individual that was being talked about.
So, option B is correct.
Learn more about determiners here:
https://brainly.com/question/1790836
