Question of TOEIC: difference between which and that

that’s a question of TOEIC

here is that question>
It is an agreement () i was talking about.

1.which
2.that
the answer is that
is there anybody who could explein to me why?

thx very much :?:

Hi,

Have a look at some material I’ve written for the site:

Relative Pronoun
Relative Pronoun (2)
Relative Pronoun (3)

Alan