Answer:
C. ozone
Step-by-step explanation:
Ozone is an allotropic form of oxygen, consisting of 3 atoms (O3), which has the characteristics as: unstable gas, diamagnetic, P.E. -112 ° C, at room temperature has blue color and characteristic smell. Ozone is also an extremely strong oxidizer, second only to fluorine, and reacts faster than O2.
Ozone concentration is a result of its high reactivity: a balance between its production and destruction generating a high and low concentration layer. This layer is called the "ozone layer", is located in the stratosphere, and is about 15 km thick. It is responsible for the protection of the earth against U.V (ultra violet) radiation from the sun. And to prove that ozone can bring more benefits, there is already medical ozone that increases cell oxygenation.
On the other hand, ozone can cause harm and is responsible for pollution in large urban centers, in this case it is found in the troposphere: the lowest layer of the atmosphere. Tropospheric ozone is man-made as a result of smoke generated by combustion engines and power plants.
Automobile exhaust and industrial emissions release a range of nitrous oxide (NOx) gases and volatile organic compounds (VOC), byproducts of burning gasoline and coal. The oxygen atoms released by NOx and VOC attack the oxygen molecules and form ozone by the action of sunlight.