Statement (A) :Based on properties the elements are classified into metals, non-metals and metalloids.

Statement (B) :Oxygen is an element

Statement (C) :Iron sulphide is a compound.

The matter can be divided into metals, non-metals and metalloids based on the properties of matter. Element is a pure substance formed with same kind of atoms. Ex: O, N. C , H etc Compound is a substance which is formed by the combination of two or atoms of different elements in certain ratio $\mathrm{EX}:{\mathrm{H}}_2\mathrm{O} \mathrm{and} \mathrm{FeS}$