Which layer contains the ozone layer and shows increasing temperature with altitude?

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Thermosphere

Answer: (B)

The key idea is how temperature changes with height in different atmospheric layers and where ozone is located. The ozone layer sits in the stratosphere. There, ozone absorbs ultraviolet radiation from the Sun, and this energy absorption warms the air. Because of this heating, temperature increases with altitude within the stratosphere. That combination—ozone concentrated in this layer and a warming trend as you go higher—makes the stratosphere the best fit. In contrast, the troposphere cools with height, the mesosphere also gets cooler with altitude, and while the thermosphere warms with height, it contains very little ozone, so it doesn’t match the clue about the ozone layer.