Calculate $\Delta H_{C-H}$ from the following data: $\Delta H^{\circ}_{combustion}$ of ethane and propane are $-372$ and $-530\: kcal/mol$ respectively, $\Delta H_f^{\circ}$ of $CO_2(g)$ and $H_2O(l)$ are $-94$ and $-68\: kcal/mol,\: \Delta H^{\circ}$ for $C(graphite) \rightarrow C(g)\: is\: 172\: kcal \: and\: \Delta H_{H-H} \: is\: 104 \: kcal.$

Question

$\begin {array} {1 1} (A)\;-99\: kcal/mol & \quad (B)\;99\: kcal/mol \\ (C)\; 82\: kcal/mol & \quad (D)\;- 82\: kcal/mol \end {array}$