Answer:
e. is produced by the absorption of UV radiation.
Explanation:
The thermosphere is a layer of Earth's atmosphere which is directly above the mesosphere and below the exosphere. It extends from about 85 to 500 km altitude above the earth.
In the thermosphere, the temperature is strongly dependent on the level of solar activity. When the Sun is very active and emitting more high energy radiation, the thermosphere becomes hotter by X-ray and UV radiation absorption.