A student says that all pure substances are elements. Do you agree? Why or why not? Question 14 options: I agree. Pure substances include only single atoms made of one element. I disagree. Elements are not pure substances. All pure substances include only molecules and compounds, which are more complex. I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds. I disagree. All pure substances are also mixtures.