Which landform is characterized as a sinuous ridge formed by glacial drift?

An esker is a landform commonly associated with glacial activity, characterized as a long, winding ridge made up of sand, gravel, and other materials deposited by glacial meltwater. These structures typically form beneath a glacier when meltwater flowing through tunnels in the glacier carries sediments, which are then deposited as the water slows down after exiting the glacier. This distinct formation results in the sinuous appearance of eskers. The sedimentary layers are often layered and can vary in size, reflecting the dynamics of glacial melt and flow.

In contrast, kames are typically irregularly shaped hills composed of sand and gravel, formed by the deposition of sediment in glacial environments but do not take the sinuous ridge shape characteristic of eskers. Alluvial fans are depositional landforms created in arid regions where streams lose energy and deposit sediment, while loess plains consist of wind-deposited silt and are not associated with glacial drift. Thus, the unique formation process and structure of eskers clearly distinguish them from other landforms listed.