Ozone is a gas {that} occurs naturally in small (trace) amounts in the upper atmosphere..ozone proctects life on earth from the sun's ultraviolet (uv) near the earth's surfacew, zone is created by chemical reaactions between air pollutants from vehicke exhaust, gasoline vapors, and other emissions. at ground level, high concentrations of ozone are toxic to people and plants -nasa ozone hole watch

which statment best summarizes the main idea being expressed?
a. ozone needs to be at high levels throughout the atmosphere because people and plants need it to live.
b. ozone is toxic, so its presence in the atmosphere is dangerous for the environment.
c. ozone levels can rise or fall without significantly affecting people or the environment.
d. ozone is necessary high in the atmosphere but dangerous in the lower atmosphere.

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