Which one of the following would require the largest amount of energy to cause dissociation

Question

$\begin{array}{1 1}(a)\;C\equiv C\;in\;C_2H_2\\(b)\; N\equiv N\;in\;N_2\\(c)\;C= C\;in\;C_2H_4\\(d)\;N\equiv N\;in\;N_2H_2\end{array}$