Which type of terrain would likely have contour lines representing a gentle slope?

Low hills typically have contour lines that are spaced closely together, indicating a gentle slope. When observing contour lines on a topographical map, a less pronounced elevation change over a distance results in these lines being further apart. Gentle slopes, such as those found on low hills, will show this characteristic with a gradual rise in elevation.

In contrast, steep cliffs would be represented by contour lines that are very close together, indicating a rapid change in elevation over a short distance. Deserts and flat plains would not exhibit slopes at all; rather, they would reflect minor elevation changes either with very few contour lines or none at all, suggesting flatness or minimal terrain variation. Therefore, the presence of low hills on a terrain map correlates well with contour lines that illustrate gentle slopes, affirming that this is the correct choice.