Which of the following statements is true about the ozone layer?

• A. It is located in the troposphere
• B. It is important for blocking harmful UV radiation
• C. It exists at an altitude below 5 km
• D. It is uniformly distributed at all altitudes

Answer: (B)

The ozone layer is crucial for life on Earth because it absorbs the majority of the sun's harmful ultraviolet (UV) radiation. By doing so, it protects living organisms, including humans, from the adverse effects of UV exposure, such as skin cancer and cataracts, as well as harmful impacts on ecosystems.

This function of the ozone layer is paramount, as increased UV exposure can lead to significant health and environmental issues. It primarily resides in the stratosphere, a layer of the atmosphere that is situated above the troposphere, which emphasizes the importance of understanding its correct position and role in the atmosphere.

In contrast to the provided answer, the other statements do not accurately reflect the nature of the ozone layer. Its location is not within the troposphere, nor does it exist below an altitude of 5 km, and it is not uniformly distributed at all altitudes; rather, its concentration is highest in the stratosphere around 10 to 30 km above the Earth's surface.