Amount of oxalic acid present in a solution can be determined by its titration with ${\text{KMnO}}_4$ solution in the presence of ${\text{H}}_2{\text{SO}}_4$. The titration gives unsatisfactory results when carried out in the presence of $\text{HCl}$ because $\text{HCl}$:

1. A
   gets oxidized by oxalic acid to chlorine
2. B
   furnishes ${\text{H}}^{+}$ ions in addition to those from oxalic acid
3. C
   reduces permanganate to ${\text{Mn}}^{2+}$
4. D
   oxidizes oxalic acid to carbon dioxide and water