Which choice contains a broad pronoun reference?

we need rain. this would clear the dust from the sky and end the drought.
we need rain to clear the dust from the sky and end the drought.
we need rain that would clear the dust from the sky and end the drought.
to clear dust from the sky and end the drought, we need rain.

the tone of the passage is sympathetic to the forbidden love of romeo and juliet. the nurse plays a significant role in the play. she is responsible for making their meeting again possible. additionally, there is a sense of warning in the choice of words of the nurse. she seems to be authoritative when she calls romeo "scurvy knave", and at the same time the fact that she addresses to him as "sir" reflects respect. the nurse is "vexed", this word describes her confused state of mind. on the one hand, she finds romeo a fine and eloquent man, but on the other, it is thought that man's nature forces men to try to trick women.