Question

what was the name of the man who you met yesterday? (omission or reduce)

Answer 1

the answer is : what was the name of the man whom you met yesterday?

Answer 2

Answer:

what was the name of the man whom you met yesterday? (correct)

Explanation:

Note: whom is used in the objective case.

'who' is the nominative case and it does not fit as a Relative Pronoun here.

Now one more point worth to be noted here is:

when the relative Pronoun is the object is a preposition,we may put the preposition at the end of the clause, but then the relative pronoun is usually omitted

The man I owed money to is admitted in the hospital. (Whom is omitted)

There is no room i can stay in. (Which is omitted)