Which of the following statements about loess is true?

Loess is a type of sediment primarily composed of silt-sized particles that are typically formed by wind action. Its significance in agriculture, particularly in the American Midwest, stems from its fertility. The fine particles of loess are rich in minerals and provide excellent conditions for growing crops, as they retain moisture well and have a porous structure that aids in drainage and root penetration. This characteristic has made regions with loess deposits particularly productive for farming, contributing to the agricultural success and economic development of the American Midwest.

In contrast, the other statements are not accurate representations of loess. It is not primarily carried by water, as that would refer to sedimentation processes associated with river or lake environments, rather than wind. Though loess can vary in mineral content, it is generally considered to have a higher mineral content compared to other soil types such as clay or sand. Additionally, loess is not particularly dense; it is usually characterized by a loose, crumbly texture that allows for good aeration and fertility, further aiding agricultural practices.