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.

Relax

Respuesta :

We need rain that would clear the dust from the sky and end the drought. 

NOT:
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.
To clear dust from the sky and end the drought, we need rain.