In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is $CH_3OH (\ell) + \frac{3}{2} O_2 (g) \to CO_2 (g) + 2H_2O (\ell)$ at 298 K standard Gibb's energies of formation for $CH_3OH (\ell), H_2O (\ell)$ and $CO_2 (g)$ are $-166.2, -237.2$ and $-394.4$ $kJ\; mol^{-1}$ respectively. If standard enthalpy of combustion of methanol is $-726\; kJ\; mol^{-1}$, efficiency of the fuel cell will be

Question

( A ) 90%
( B ) 97%
( C ) 80%
( D ) 87%