If you are trying to pick a phrase at the end, I would go for either A. or D.
The answer is A, how does country's population size contribute to it's levels of air pollution
She sat on the old wooden bench, clutching her purse tightly in her lap, the crazy old woman felt bad, as she looked at the ground.
I'm on the same assignment right now. Did you every get it, I also need help with it.
