What is one major environmental impact of ozone depletion?

The correct answer highlights a significant consequence of ozone depletion, which is the reduction in marine life. The ozone layer plays a crucial role in filtering out harmful ultraviolet (UV) radiation from the sun. When the ozone layer is depleted, more UV radiation reaches the Earth's surface, particularly affecting marine ecosystems. This increased exposure can harm phytoplankton, which form the base of the aquatic food web. The decline in phytoplankton populations can have cascading effects on the entire marine ecosystem, leading to reduced biodiversity and negatively impacting fish populations and other marine organisms that rely on these primary producers for sustenance.

In contrast, the other options relate to agricultural and forest growth scenarios that are either benefitted or unaffected by ozone depletion in different contexts. While agricultural output and forest growth rates may be influenced by other environmental factors, they do not directly illustrate the critical link between ozone levels and the health of marine ecosystems. Additionally, increased soil fertility is not a recognized environmental impact of ozone depletion. Therefore, the significant decline in marine life is a direct and relevant outcome of increased UV radiation stemming from the thinning of the ozone layer, illustrating a serious threat to oceanic health and biodiversity.