Identify the incorrect statement from the following:

• A
  Oxygen exhibits only $-2$ oxidation state.
• B
  The order of catenation property of Group $14$ elements is $C \gg Si > Ge \approx Sn$.
• C
  Carbon has the ability to form $p\pi-p\pi$ multiple bonds with itself.
• D
  $ECl_3$ ($E = B$ and $Al$) is a monomer when $E = B$ and a dimer when $E = Al$.