Final answer:
Water is the biggest agent of erosion, shaping the earth's surface through the force of running water or ocean waves.
Step-by-step explanation:
The biggest agent of erosion is water. Water erosion occurs when water flows across the earth's surface and wears away the soil and rocks. This can happen through the force of running water, such as rivers and streams, or the movement of waves along coastlines.
For example, in river valleys, water erosion can carve out deep channels over time. Similarly, the erosion caused by ocean waves can create cliffs and caves along rocky beach coastlines.
Overall, water is a powerful force that can reshape the earth's surface through erosion.