Which of the following terms describes an accumulation of rocky, sandy, or clayey material deposited at the end of a glacier?
a. moraine
b. loess
c. dune
d. esker

Option (D)

Explanation:

Eskers are the long ridges that are comprised of rocks, sands and clay particles and are deposited towards the end of the glaciers. These are fluvioglacial depositional features. These particles are exposed after the glaciers recede. These ridges are formed parallel to the earlier flow direction of ice. The size of eskers is generally smaller as it carries smaller particles such as rocks, sands, and gravels, in comparison to the different type of moraines. It is because the flow velocity decreases as the glaciers melt. So, these eskers are formed at the end of the glaciers.

Thus, the correct answer is option (D).