Which one of the following is used to remove ink and rust stains on cloth?

Explanation

Rust is hydrated ferric oxide, `Fe_(2)O_(3).x H_(2)O`. Oxalic acid produces oxalate ion `C_(2)O_(4)^(2-)` which is a chelating agent and forms soluble complex with Fe(III) present in rust.
`Fe_(2)O_(3)+6C_(2)O_(4)^(2-)+6H_(3)O^(+)rarrunderset("Soluble compelx")(2[Fe(C_(2)O_(4))_(3)]^(3-))+9H_(2)O`