Which of the following is an ecosystem service provided by grasslands?

Grasslands provide several important ecosystem services that contribute to environmental health and sustainability. Erosion control is one of the main benefits provided by grasslands. The dense root systems of grasses help to bind the soil together, reducing the risk of soil erosion by wind and water. This stabilization of the soil is crucial for maintaining soil health, supporting agricultural productivity, and preventing sedimentation in waterways.

In contrast, while water purification is a significant ecosystem service associated with wetlands and forested areas, it is not primarily attributed to grasslands. Urban heat island mitigation refers more to the effects of urban forests and greenery, which help lower temperatures in urban areas, not specifically to the function of grasslands. Similarly, deriving fossil fuels is not an ecosystem service but rather a process of extracting non-renewable resources that can harm ecosystems and undermine their services. Thus, the role of grasslands in preventing erosion is essential, making it the correct answer.