Concept:A crescent-shaped sand hill formed by wind deposition in dry regions is a barchan dune.
Explanation:The statement describes a “crescentic” shape, which means moon-shaped, with its tips or horns pointing in the direction the wind blows.
This landform is created by wind deposition in arid and desert environments.
Among the given options, only a barchan dune has this characteristic crescent form.
Loess is wind-deposited silt but it does not form crescentic hills.
Alluvial soil and silty soil are mainly deposited by water, not wind, so they do not match the description.
Answer:B. barchan dune