Amount of oxalic acid present in a solution can be determined by its titration with `KMnO_(4)` solution in the presence of `H_(2)SO_(4)`. The titration gives unsatisfactory result when carried out in the presence of HCl because HCl
A. furnishes `H^(+)` ions in addition to those from oxalic acid.
B. reduces permanganate to `Mn^(2+)`.
C. oxidises oxalic acid to carbon dioxide and water.
D. gets oxidised by oxalic acid to chlorine.
