In which sentence is who used correctly?

who is the person that you were discussing?
about who were you discussing?
who did you discuss with him?
who were you discussing

D) Who is the person that you were discussing?

1.d1.e2.c 3.chope this

The sentence needs a descriptor of exactly "what" will happen at gurley and marina. in this case, it is the light at the intersection turning green. in this case, the sentence could be rewritten as "the light at the intersection of gurley and montezuma will turn green exactly three seconds after the light at the intersection of gurley and marina."