Critical Reasoning

Please explain why D is the answer. I can not understand its explanation.

Conclusion by author: Non-urban areas are now affected by excessive air pollution.

Evidence provided by author: More people living in non-urban areas are suffering from illnesses caused by excessive air pollution.

To weaken this argument, we need to find alternative reasons to why there has been a hike in the number of people suffering from illnesses caused by air pollution in the non-urban areas.

The answer D offers an alternative explanation to why the number of air pollution related illnesses have gone up (Eg. Migraine which is not considered as an illness caused by air pollution in the past, are counted in as a symptom.)

Hope that helps!

Based on your answer, if people who suffer from illnesses caused by air-pollution move to non-urban areas, then the evidence given by the author cannot be justified.

i think that ther correct one it's option D