AP Environmental Science

Answer: C - The highest level of the atmosphere is the exosphere.

Key Takeaway: The Earth’s atmosphere is made up of many layers: the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere. The troposphere is closest to the surface of the Earth, at about 7 miles above. The exosphere is the very highest level of the atmosphere, where the atmosphere begins to blend into outer space.