Final answer:
A compound is a molecule containing two or more different elements chemically combined in a fixed proportion, such as water (H2O) or methane (CH4), and has unique properties distinct from the elements it comprises.
Step-by-step explanation:
When you ask what is a compound, the correct answer is that it is C) A molecule containing two or more elements. A compound is a substance that contains two or more different elements chemically combined in a fixed proportion. For instance, water is a compound composed of two hydrogen atoms and one oxygen atom, represented by the formula H₂O. In another example, methane (CH₄) is a compound that has a consistent ratio of one carbon atom to four hydrogen atoms. Compounds have unique properties that are distinct from the elements they are composed of, and they are held together by various types of chemical bonds.