Characteristics of the thermosphere

The aurora lights mostly occur in the thermosphere. it is directly above the mesosphere and below the exosphere. temperatures in the upper thermosphere can range from about 500° C (932° F) to 2,000° C (3,632° F) or higher, and are about 200° hotter in the daytime than night. air density is low, so much of it is considered out space. 

“d” is the answer to the question