The correct answer is C. Oxalic acid solution.
Oxalic acid is a strong acid that can be used to remove rust stains on cloth. It is available in both liquid and powder form. To use oxalic acid to remove a rust stain, mix it with water according to the instructions on the product label. Apply the solution to the stain and let it sit for the amount of time specified on the label. Rinse the solution off with water and then wash the cloth as usual.
Kerosene, lime, and petrol are not effective at removing rust stains on cloth. Kerosene is a flammable liquid that can be used to clean a variety of surfaces, but it is not effective at removing rust stains. Lime is a mineral that can be used to clean and whiten surfaces, but it is not effective at removing rust stains. Petrol is a flammable liquid that can be used to fuel engines, but it is not effective at removing rust stains.
Oxalic acid is the only option that is effective at removing rust stains on cloth. It is a strong acid that can dissolve the rust, making it easy to remove. It is available in both liquid and powder form, and it is easy to use.