Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to make grooming comfortable for older dogs [title] Create a no-skid surface. [step] Older dogs are more prone to slipping and falling, especially if they have mobility problems like arthritis. For your older dog's comfort, a no skid surface is important.

Ending1: [substeps] Lay down mats in front of or behind your older dog. This will keep him from slipping and brushing. Ending2: [substeps] A rubber surface, like a bathmat, is good to prevent your dog from slipping. You can also allow your dog to lie down. Ending3: [substeps] If you find your dog unsteady on its feet, you may need to have them slightly elevated. For example, if you're on a tight escalator, a slightly elevated hand rail can be underneath. Ending4: It reduces friction with your hands and feet. To create a skid surface, make sure that there is no slime or gravel on top of the surface.

Answer format: ending1/ending2/ending3/ending4