Which natural process can help protect coastlines?

The growth of vegetation on sand dunes plays a crucial role in protecting coastlines. Vegetation helps stabilize the sand through root systems, which bind the sand together, preventing erosion caused by wind and water. Well-established plant life traps sand particles, leading to the accumulation of sand over time and creating a natural barrier against storm surges and wave action. This natural fortification can significantly reduce the impact of coastal erosion and protect inland areas from flooding.

The other options, while potentially beneficial in other contexts, do not directly contribute to the maintenance and protection of coastlines through natural processes. For instance, increasing tourism on beaches might lead to greater human activity that can worsen erosion and environmental degradation. Construction of artificial islands can disrupt natural habitats and may not effectively mitigate erosion. Pollution reduction efforts, although vital for overall environmental health, do not specifically address the physical stabilization of coastal areas like vegetation does.