Describe
2. What is the structure of Earth's atmosphere?

The atmosphere consists of 4 layers: the troposphere, stratosphere, mesosphere, and thermosphere. The troposphere is the lowest layer of the atmosphere. This is the layer where we live and where weather happens. Temperature in this layer generally decreases with height. The boundary between the stratosphere and the troposphere is called the tropopause. Above the tropopause lies the stratosphere. In this layer the temperature increases with height. This is because the stratosphere houses the ozone layer. The ozone layer is warm because it absorbs ultraviolet (UV) rays from the sun. The mesosphere is the layer above the stratosphere.This layer also contains ratios of nitrogen and oxygen similar to the troposphere, except the concentrations are 1000 times less and there is little water vapor there, so the air is too thin for weather to occur. The thermosphere is the uppermost layer of the atmosphere. In this layer the temperature increases with height because it is being directly heated by the sun.

I got this info from North Carolina Climate Office.

Hope this helps!!

a is the answer i believe.