Answer: D - It is composed of two or more substances that retain their own chemical properties.
Saltwater is considered a mixture because it is a combination of two or more substances that are physically combined but not chemically combined. In the case of saltwater, the substances are water (H2O) and salt (typically sodium chloride, NaCl). The salt and water are physically combined, meaning that the salt dissolves in the water, but they have not undergone a chemical reaction to form a new substance. The properties of saltwater, such as its taste and conductivity, are different from the properties of the individual components (salt and water), and each component retains its own chemical identity. Therefore, saltwater is considered a mixture.
