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 results 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. Get oxidised by oxalic acid to chlorine