Rearrange the following ($I$ to $IV$) in the order of increasing masses and choose the correct answer (Atomic mass: $N=14, O=16, Cu=63$).
$I.$ $1$ molecule of oxygen
$II.$ $1$ atom of nitrogen
$III.$ $1 \times 10^{-10} \ g$ molecular weight of oxygen
$IV.$ $1 \times 10^{-10} \ g$ atomic weight of copper

• A
  $II < I < III < IV$
• B
  $IV < III < II < I$
• C
  $II < III < I < IV$
• D
  $III < IV < I < II$