Please choose the correct ending to complete the given sentence: Health: [header] How to operate a wheelchair safely outdoors [title] Stay on even surfaces. [step] Uneven surfaces can make any wheelchair get off balance. Even when someone is pushing a wheelchair, an uneven surface can cause harm.

Ending1: Try to stay within an even surface if you're able to. [title] Avoid climbing or leaning on bare rocks or concrete. Ending2: When you're walking around with someone, always make sure that you stay on a flat surface without access to a handrail. That way, you can avoid debris that might injure someone in the event of a fall. Ending3: Make sure you stay on this surface and do not place yourself in harm's way. [substeps] Wear protective clothing when you use your wheelchair. Ending4: Users and caregivers alike need to stick to slopes that only go up to a gradient of 20% and are dry, solid, and straight. [substeps] Avoid inclines, slopes, staircases, and curbs.

Answer format: ending1/ending2/ending3/ending4