Two substances,$A$ and $B$,were made to react to form a third substance,$A_2B$,according to the following reaction: $2A + B \to A_2B$. Which of the following statements concerning this reaction are incorrect?
$(i)$ The product $A_2B$ shows the properties of substances $A$ and $B$.
$(ii)$ The product will always have a fixed composition.
$(iii)$ The product so formed cannot be classified as a compound.
$(iv)$ The product so formed is an element.

• A
  $(i), (ii)$ and $(iii)$
• B
  $(i), (iii)$ and $(iv)$
• C
  $(ii), (iii)$ and $(iv)$
• D
  $(ii), (iv)$ and $(i)$