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)

which

what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

> geologic time scale <

radioactive elements

1. is geographic distribution

2 is increasing complexity

3 is transitional forms

here is the answer

water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. weathering is the breaking down or dissolving of rocks and minerals on earths surface. once a rock has been broken down, a process called erosion transports the bits of rock and minerals away.