Which of the following is primarily composed of fine particles smaller than sand but larger than clay?

Silt is primarily composed of fine particles that are larger than clay but smaller than sand, typically ranging in size from 0.002 mm to 0.05 mm in diameter. This unique particle size gives silt distinct physical properties, such as a smooth texture and good drainage capabilities, while also retaining moisture better than sand due to its smaller particle size.

Loamy soil refers to a mixture of sand, silt, and clay, which combines the beneficial properties of all three to support plant growth, but it does not exclusively define the characteristics of the finer particles. Clay consists of even smaller particles than silt, measuring less than 0.002 mm, and has very different drainage and nutrient-holding properties. Organic matter is comprised of decomposed plant and animal residues, playing a crucial role in soil health but not defined by particle size.

Thus, silt stands out as the correct answer due to its specific range of particle size and its role in the classification of soil types.