GMAT Critical Reasoning (CR) | Re: At a recent conference on environmental threats to the North

For answer choice (D), imagine Germany has been dumping mercury into its rivers, mercury which eventually reaches the North Sea.

(D) is saying that it is important that all of the mercury reach the North Sea. If mercury causes environmental damage, then it doesn't matter whether all of it reaches the North Sea. The mercury is causing damage. Therefore we can eliminate (D) based on the word 'all.'

Now let's say, Germany dumps a lot of oxidimide (just made that up) into its river. A uniform control