In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is ${\text{CH}}_3\text{OH}(l)+\frac{3}{2}{\text{O}}_2(g)\to {\text{CO}}_2(g)+2{\text{H}}_2\text{O}(l)$. At $298\text{K}$ standard Gibb’s energies of formation for ${\text{CH}}_3\text{OH}(l)$, ${\text{H}}_2\text{O}(l)$ and ${\text{CO}}_2(g)$ are $-166.2$, $-237.2$ and $-394.4{\text{kJ mol}}^{-1}$ respectively. If standard enthalpy of combustion of methanol is $-726{\text{kJ mol}}^{-1}$, efficiency of the fuel cell will be:

1. A
   $80\%$
2. B
   $87\%$
3. C
   $90\%$
4. D
   $97\%$