Which reaction is this?

${\mathrm{CaCO}}_3 \to \mathrm{CaO} + {\mathrm{CO}}_2$

A chemical reaction known as decomposition occurs when one reactant separates two or more products from one another. It is a combo reaction's opposite. For instance, in a displacement reaction, the element's atom is swapped out for one from another. A chemical equation will demonstrate the chemical reaction. The transition from reactants to products is symbolized by it. The reactant side is shown on the left, and the reaction's result is shown on the right. The decomposition reaction occurs in our regular chemistry lab. As the food decomposes, heat, carbon dioxide, and water are produced. Simple units of food such as protein, lipids, and carbs will be broken down.

The given reaction ${\mathrm{CaCO}}_3 \to \mathrm{CaO} + {\mathrm{CO}}_2$ is a decomposition, as the calcium carbonates decompose calcium oxide and carbon dioxide.

Hence, the correct answer is C.