Which type of surface is most likely to form scree?

Scree typically forms on mountain slopes due to the processes of weathering and erosion. This loose material, consisting of broken rock fragments, occurs when rocks on steep slopes break apart due to freeze-thaw cycles, temperature changes, and other geological processes. Gravity plays a significant role in the accumulation of scree, as rock debris naturally falls down slopes that can no longer support the fractured rocks.

In contrast, flat plains usually have a more stable surface with little movement of rocky material, while riverbeds are primarily composed of sediment deposited by flowing water, and coastal regions are influenced by wave action, which shapes the landscape differently. This makes mountain slopes the most suitable environment for the formation of scree, driven by natural forces in a way that isn't as prominent in the other listed surfaces.