Which of the following refers to substances made of more than one element combined?

The term that refers to substances made of more than one element combined is indeed compounds. Compounds are formed when two or more different elements chemically bond together in fixed proportions, resulting in substances that have unique properties distinct from the individual elements themselves. For example, water (H2O) is a compound consisting of hydrogen and oxygen in a specific ratio, and it exhibits properties different from those of pure hydrogen or pure oxygen.

In contrast, elements are pure substances that cannot be broken down into simpler substances by chemical means and consist of only one type of atom. Pure substances can refer to either elements or compounds but do not inherently describe a combination of elements. Mixtures, on the other hand, involve two or more substances mixed together but not chemically bonded, which allows each component to retain its individual properties. Thus, the focus on compounds emphasizes the chemical combination and fixed ratio of elements, making it the correct choice.