Answer the following question given this paragraph: When two or more pure substances are combined together, a mixture is formed. Unlike pure substances, mixtures have a variable composition. Variable composition indicates that the relative proportions of the mixtures components may vary, and they can be separated by physical methods. There are two main types of mixtures. Q: Unlike pure substances, mixtures have a what? Choices: - efficient composition - unique composition - complex composition - variable composition A:
variable composition