The correct increasing order of $C-H(A)$, $C-O(B)$, $C=O(C)$ and $C\equiv N(D)$ bonds in terms of covalent bond length is:

• A
  $A < D < C < B$
• B
  $A < C < D < B$
• C
  $D < C < B < A$
• D
  $D < C < A < B$