Which components are included in nonstructural carbohydrates?

Nonstructural carbohydrates primarily refer to simple sugars and readily digestible carbohydrates found in plants. The correct answer includes components such as plant starch, pectin, and sugar, which are categorized under nonstructural carbohydrates.

Plant starch serves as a significant energy source and is commonly stored in plant tissues, providing a readily available form of energy. Pectin, which is found in the cell walls of fruits and vegetables, acts as a gel-forming substance and is easily fermentable, making it digestible for ruminants. Sugars, which include simple carbohydrates like glucose and fructose, are also key energy sources that can be rapidly utilized by dairy cattle.

In contrast, cellulose and lignin are associated with the structural components of plant cell walls and fit into the category of structural carbohydrates, which are not as easily digestible. Proteins and vitamins, while crucial to animal nutrition, are not classified as carbohydrates at all, nor do minerals and water have any relation to carbohydrate classification. Hence, the components of nonstructural carbohydrates are correctly identified in the chosen answer.