Which of the following is classified as a type of aggregate?

Gravel is classified as a type of aggregate because it consists of small, loose pieces of rock that are often used in construction as a base material or in concrete. Aggregates are materials that are mixed into concrete or asphalt to provide strength and bulk. Gravel, being composed of naturally occurring stones, is one of the most common types of coarse aggregates used in various construction projects, including roads, foundations, and drainage systems.

In contrast, topsoil is a layer of soil that contains organic material, and while it is essential for planting and gardening, it does not serve the same function as an aggregate. Water is a crucial component in concrete mixing but is not classified as an aggregate itself; it acts as a solvent and hydration medium. Cement, while a binding agent in concrete and mortar, is not categorized as an aggregate but rather as a powder that, when mixed with water and aggregates, forms a cohesive material.