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 sequence correctly shows the path of carbon dioxide during repiration?

What pattern of migration do whales follow?

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.