What do rolling terrains primarily consist of?

Rolling terrains primarily consist of hilly areas, which is why the selected answer is correct. This type of terrain is characterized by a series of hills or gentle slopes, rather than flat lands or steep cliffs. Rolling hills can vary in height and shape but generally create a smooth, undulating landscape that distinguishes them from other more uniform geographical features.

In contrast, flat landscapes lack the elevation changes inherent to rolling terrains, and steep cliffs present abrupt changes in elevation that do not capture the gradual transitions of rolling hills. Desert flats are largely flat and arid regions, which also do not align with the features associated with rolling terrains. Therefore, the presence of hills is the definitive characteristic that classifies rolling terrains.