Formic acid is obtained when -

Options

1. ACalcium acetate is heated with conc. ${H}_{2}{SO}_{4}$
2. BCalcium formate is heated with calcium acetate
3. CGlycerol is heated with oxalic acid at $373K$
4. DAcetaldehyde is oxidised with ${K}_{2}{Cr}_{2}{O}_{7}$ and ${H}_{2}{SO}_{4}$