Explanation
Among the given options, the pollutant emitted from vehicles that will have the maximum impact on the respiratory system is (D) PM2.5.
PM2.5 refers to particulate matter with a diameter of 2.5 micrometers or smaller. These tiny particles can penetrate deep into the respiratory system, reaching the lungs and even entering the bloodstream. Exposure to PM2.5 can lead to various respiratory problems, including asthma, bronchitis, and other respiratory diseases. CO2 (carbon dioxide) is a greenhouse gas and contributes to climate change but does not directly impact the respiratory system. SO2 (sulfur dioxide) and PM10 (particulate matter with a diameter of 10 micrometers or smaller) can also have respiratory effects but generally have a lower impact compared to PM2.5 particles.