Answer: Option (A) is the correct answer.
Step-by-step explanation:
A pure substance is defined a substance that contains atoms of same element and it has constant composition throughout the sample.
For example, sulfur,
, nitrogen etc are all pure substances.
Whereas a compound is a substance that contains two or more substances which are combined together in a fixed composition.
For example, NaCl is a compound.
When components of solute are uniformly distributed in a solvent then the solution is known as homogeneous solution.
When components of solute are non-uniformly distributed in a solvent then the solution is known as heterogeneous solution.
Thus, we can conclude that elements are considered pure substances.