The thermosphere is the hottest layer because it . is heated directly by the sun is closest to the ground is heated by the Earth's surface contains the ozone layer

Option (1)

Explanation:

The thermosphere is the layer that lies between the mesosphere and the exosphere, extending from a height of about 85 km to about 500 km above the surface of the earth. In this layer, the temperature and height are directly proportional to each other. There occurs a high temperature in this layer due to the large absorption of the incoming radiations coming from the sun. This layer has a great significance, as the charge particles present in this layer useful for the large scale radio communication.

Thus, the correct answer is option (1).