Answer: All substances are composed of elements.
Explanation: Matter is anything which has mass and occupies space.
The substances can be made up element alone like Helium (He).
They can be made up of molecules of elements also like hydrogen
They can also be made up of molecules of compounds like carbon dioxide
They can be made up of mixtures like salt solution in water.
Since all the mixtures, compounds and molecules consists of elements. Therefore, all the substances are composed of elements.