What do we call a gentle slope formed from material deposition at the inner bend of a river?

A gentle slope formed from material deposition at the inner bend of a river is referred to as a slip-off slope. This is created by the reduction of river velocity on the inside bend, where sediment tends to accumulate instead of being eroded. As the water flows more slowly in this region, it loses energy and drops the sediment it carries, thus forming a gently sloping bank.

This process is tied closely to river meandering, where the water frequently erodes the outer bend (creating a river cliff) while depositing materials on the inner bend, leading to the formation of the slip-off slope. The accumulation of material also impacts the river's morphology and can create diverse habitats along the riverbank.

The other options refer to different geographical features associated with rivers. A river cliff is typically associated with erosion on the outer bend of a meander, while banks are the sides of a river where water flows, and a floodplain is an area adjacent to the river that is subject to flooding and deposition during high water events.