Which of the following is classified as a chemical compound?

A chemical compound is defined as a substance formed when two or more different elements are chemically bonded together. Water is a classic example of a chemical compound because it consists of two hydrogen atoms covalently bonded to one oxygen atom (H₂O). This combination results in properties that are distinct from those of the individual elements, oxygen and hydrogen.

In contrast, the other options provided (oxygen, hydrogen, and carbon) are classified as elements. An element is a pure substance that cannot be broken down into simpler substances by chemical means and is represented on the Periodic Table. These elements stand alone without forming any compounds unless they bond with other elements. Therefore, while they are important constituents of various compounds, they do not themselves qualify as chemical compounds. This distinction clarifies why water is the only correct answer among the choices.