Please choose the correct ending to complete the given sentence: Home and Garden: [header] How to remove ink stains from cement [title] Combine 2 tablespoons of sodium perborate and 1 cup of very hot water in a large bowl to make a sodium perborate hot bleach solution. [title] Add whiting to the solution until the mixture forms into a thick paste. [step] Whiting can be bought in some paint stores.

Ending1: [title] Let the mixture sit for 30 minutes. [step] The mixture will transfer to stained concrete to prevent the stain from spreading to the rest of the concrete. Ending2: [title] Apply the paste to the stain with a sponge or toothbrush, to avoid scratching the cement. [title] Rinse the vinegar mixture from your cement stain with chlorine. Ending3: If whiting is not available, you can use kitchen flour. [title] Thoroughly wet the surface to be treated with clean, clear water. Ending4: [substeps] It will help to get rid of as much grease as possible in the process of applying the paste. Your rag should be able to comfortably slip into the bleach solution.

Answer format: ending1/ending2/ending3/ending4