Which of the following statements are true for pure substances?
$(i)$ Pure substances contain only one kind of particles.
$(ii)$ Pure substances may be compounds or mixtures.
$(iii)$ Pure substances have the same composition throughout.
$(iv)$ Pure substances can be exemplified by all elements other than nickel.

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