It’s not necessary for a solution to require changes in international law. What if the laws already exist, but are just ineffective because nations won’t abide by them willingly, because they don’t want to give up power? We don’t necessarily need new laws.

The author concludes that there cannot be a solution because nations wouldn’t willingly give up power, and laws are futile without willing compliance.

But if nations didn’t even need to give up power, then nations might be willing to comply. (B) shields us from this loophole.

The argument is that there cannot be a solution because effective laws require nations to abide by them, which won’t happen because nations won’t cede power. This could be true even if there was ultimately no solution — there could be other reasons why a solution won’t happen.

(D) deals with the the causes and effects of pollution, whereas the argument deals with finding a solution. Even if the pollution is produced by many nations or impacts few nations, this wouldn’t affect the argument.

(E) does not impact the argument, because what is true of current laws is not necessarily true of future laws. Additionally, if nations were not required to give up any power, this would actually undermine the argument.