A $4.4\,\mathrm{g}$ sample of an organic acid is completely neutralised by $25.0\,\mathrm{cm^3}$ of $2.0\,\mathrm{mol\,dm^{-3}}$ sodium hydroxide solution. Each molecule of the acid contains one COOH group. Which empirical formula corresponds to the acid?
- A$\mathrm{CH_2O}$
- B$\mathrm{C_2H_4O}$
- C$\mathrm{C_3H_6O_3}$
- D$\mathrm{C_4H_8O_2}$