Which of the following statements is true regarding the impact of UV radiation?

The statement regarding the suppression of immune responses is accurate because UV radiation can indeed have an immunosuppressive effect. Exposure to UV radiation, particularly UVB rays, weakens the skin's immune response, which can reduce the body’s ability to fight off skin cancers and viral infections. This immunosuppression occurs as UV radiation affects the functioning of various immune cells in the skin, leading to a diminished local immune response.

While the other statements discuss effects that are either beneficial or misleading, they do not accurately represent the overall impact of UV radiation. For instance, while UV light can promote some aspects of plant growth by stimulating processes such as photosynthesis, excessive exposure can also be detrimental. Similarly, UV radiation is linked to an increased risk of cataracts rather than a decrease. Lastly, its effects on respiratory health are generally negative, as UV exposure does not improve respiratory conditions. Overall, the influence of UV radiation is complex and can result in various health impacts, with immune suppression being a well-documented effect.