The maximum concentration of Ozone is found in which of the following?

1. A

   Troposphere

   The troposphere holds most weather and some surface ozone as a pollutant, but not the global maximum of ozone. Column ozone is concentrated well above this layer. This option is not the key.

2. B

   Mesosphere

   The mesosphere lies above the stratosphere and is too thin and cold for the ozone maximum. Ozone declines sharply once the stratospheric peak is passed. This option is therefore wrong.

3. C

   Stratosphere

   The stratosphere contains the ozone layer, with peak concentration typically around 15 to 35 kilometres. There ultraviolet radiation splits oxygen and the resulting atoms form ozone, which then absorbs further ultraviolet. That is why the maximum ozone is found here. This option is the official key.

4. D

   Exosphere

   The exosphere is the outermost fringe of the atmosphere, with extremely low density. It cannot hold a concentrated ozone reservoir. This option is not the key.

Summary. Official key is (c) Stratosphere. The ozone layer and the highest ozone mixing ratios sit in the stratosphere, where ultraviolet-driven oxygen chemistry produces and maintains ozone. Tropospheric ozone is a lesser, often polluting, fraction. Mesosphere and exosphere lie above the peak and are too rarefied. Only (c) names the layer of maximum concentration.