It is crescentic in shape and it is formed from wind deposition in arid. The statement describes

Step 1: Analyze the question The question asks for a feature that is:

• crescent-shaped
• formed by wind deposition
• found in arid (desert) areas

Step 2: Explain the concept In deserts, wind carries sand and drops it when it slows down or meets an obstacle. This deposition builds different types of sand dunes. The main one with a crescent (curved, moon-like) shape is the barchan.

A barchan has these features:

• The horns (tips) of the crescent point downwind.
• The windward side has a gentle slope.
• The leeward (sheltered) side has a steep slip face.
• It forms where sand is limited and the wind blows steadily from one direction.

Step 3: Check each option

• A. Loess: This is fine, wind-blown silt deposited as a thick blanket, as in parts of China. It has no crescent shape, so it is wrong.
• B. Barchan dune: This is a crescent-shaped dune formed by wind deposition in deserts, so it is correct.
• C. Alluvial soil: This is deposited by rivers, not wind, so it is wrong.
• D. Silty soil: This is a soil type defined by particle size. It has no specific crescent shape, so it is wrong.

Step 4: Answer The correct option is B. barchan dune.

Tip: Link "crescent" with "barchan". Think of a crescent moon sitting on the desert sand. Also remember that the horns point the way the wind is blowing.