Anhydrous borax, $\mathrm{Na}{}_2\mathrm{B}{}_4\mathrm{O}{}_7$, is warmed with excess ethanol and concentrated $\mathrm{H}{}_2\mathrm{SO}{}_4$. Assuming complete conversion, the number of $\mathrm{B}(\mathrm{OC}{}_2\mathrm{H}{}_5){}_3$ molecules formed per formula unit of $\mathrm{Na}{}_2\mathrm{B}{}_4\mathrm{O}{}_7$ and the oxidation state of boron in the ester are:

1. A$2$; $+3$
2. B$4$; $+2$
3. C$4$; $+3$
4. D$1$; $+3$