Please help!

The EPA sets national air-quality standards for common air pollutants. The table shows the change in the concentrations of these pollutants over time and the impact on overall air quality. Reducing which pollutant resulted in the most air-quality improvement?

A. CO(carbon monoxide)

B. O3 (ozone)

C. Pb (lead)

D. NO2 (nitrite)

c

explanation:

i think

it also supports my hypothesis. if you rest first you can squeeze the clothespin more times. from the data i collected the average of the eight people concluded exercise makes your muscles more fatigued and less able to squeeze the clothespin compared to resting before squeezing.

the answer would be knowledge about cars!