I would have to say the answer is C.
A is incorrect since hydrogen is not an air pollutant.
B is incorrect because ozone is most definitely one of the top.
And D has cyanide which is a chemical for suicide during wars.
Hope this helps!
Headache, nausea, vomiting, constipation, dizziness, spinning sensation, drowsiness, slurred speech, loss of balance or coordination, swollen or tender gums, sleep problems (insomnia), nervousness, tremors, rash.
Avoid sexual activities and/or sexual priorities. Also, have a good amount of self-control
