The correct answer is: D. Mixture
Air is a mixture of gases, primarily nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%), and other gases in trace amounts. It is a homogeneous mixture, meaning that its composition is uniform throughout.
A compound is a substance that is made up of two or more elements that are chemically combined. For example, water is a compound that is made up of hydrogen and oxygen.
An element is a substance that cannot be broken down into any simpler substances by chemical means. For example, gold is an element.
An electrolyte is a substance that conducts electricity when dissolved in water. For example, salt is an electrolyte.
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