What are the three factors that influence the energy of runoff?

The correct answer identifies slope gradient, slope length, and volume of runoff as the three factors influencing the energy of runoff.

Slope gradient refers to how steep the land is; steeper slopes can cause water to flow more quickly, thereby increasing its energy. Slope length plays a significant role as well; longer slopes provide more distance for water to gain momentum before it reaches a flatter area, which can increase runoff energy. Lastly, the volume of runoff is crucial since larger amounts of water can carry more energy, increasing its potential to erode soil and transport sediment.

When considering the other options, it's essential to note that while factors like rainfall intensity and soil type are important in determining runoff characteristics, they do not directly measure the energy of the runoff in the way that slope gradient, slope length, and volume do. Similarly, factors like vegetation cover and soil moisture affect infiltration and erosion but do not contribute directly to measuring runoff energy in the same manner as the selected answer.