Scientists hoping to understand and eventually reverse damage to the fragile ozone layer in the Earth's upper atmosph...

Hello, I was so torn between A and D. A makes sense because the craft was being flown for "good" reasons in comparison to a factory. However, I feel like A can also infer that this craft is only being used once or handful of times a year whereas a factory is being used every single day. That said, this led me to hone in D because of the aforementioned reasons of A, D would be the answer because these two quantities of pollution between craft and factory are incomparable?