When excess oxalic acid si added to `CaCI_(2), CaC_(2)O_(4)` is precipitated but the solution still contains some unprecipated `Ca^(2+)` because

Options

A. `CaC_(2)O_(4)` soluble
B. oxalic acid does not ionise
C. when `H_(2)C_(2)O_(4)` is added to `CaI_(2)` HCI, is formed which is fully ionised and thus increases the `H^(+)` concentration suppresses the ionisation of `H_(2)C_(2)O_(4)` and hense the solubility product of `CaC_(2)O_(4)` is not exceeded
D. None of the above

Answer

C