Which climate conditions most likely produce a landscape with rounded hills?

Rounded hills are a feature mainly in arid and semi-arid climate regions. This due to the fact that the wind has more of an influence in the erosion process cause the soil is not protected by a layer of vegetation, or the vegetation is very scarce. The wind erodes the hill tops the most as they are the most exposed to them, and has a tendency to flatten them, so the hill slowly over time takes a rounded shape.

The sun's parallax would be 180 degrees, greater than which you can't get.  so a. would be your anwser