Which atmospheric layer contains the ozone layer?

The ozone layer is primarily located in the stratosphere, which is the second layer of Earth's atmosphere, situated above the troposphere and below the mesosphere. This layer is crucial for life on Earth as it absorbs the majority of the Sun's harmful ultraviolet radiation, preventing it from reaching the surface. By doing so, the ozone layer plays a vital role in protecting living organisms from potential harm such as skin cancer and cataracts, as well as preserving ecosystems.

The troposphere, the layer directly below the stratosphere, contains weather phenomena and is where most of the atmosphere's mass resides, but it does not contain the ozone layer. The mesosphere is located above the stratosphere and is known for its decreasing temperatures with altitude, while the thermosphere sits above the mesosphere and is characterized by very high temperatures. Neither the mesosphere nor the thermosphere contains a significant amount of ozone. Thus, the stratosphere is the correct answer as it is the layer where the ozone layer is found, serving a critical function in protecting life on Earth.