How does the speaker's use of the words they and we

Ithink it's a. but i could be wrong because it might be b. but it's not the other two

Iam confused on what u are trying to ask

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."