Which of the following is NOT one of the three major divisions of the Unified Soils Classification System (USCS)?

The Unified Soils Classification System (USCS) categorizes soils into three major divisions: coarse-grained, fine-grained, and highly organic. Coarse-grained soils consist of larger particles, such as sand and gravel, while fine-grained soils include smaller particles like silt and clay. Highly organic soils are rich in decomposed material and typically have distinct characteristics affecting their engineering properties, such as peat.

Clayey refers to a type of soil characterized specifically by the presence of clay particles, which fall under the category of fine-grained soils. While clay is an important type of fine-grained soil, referring to it as "clayey" does not represent a standalone division in the USCS. Therefore, it is not recognized as one of the three major divisions, making it the correct answer to the question.