Please choose the correct ending to complete the given sentence: Health: [header] How to protect your eyes when using a computer [title] Sit far enough away from the screen. [step] This is usually considered at least an arm's length away from the screen. To make sure your computer is positioned right, try the high-five test: if you can properly high-five your computer screen with a full arm extension, you're sitting too close.

Ending1: Try picking a seat close to the screen so you have enough comfortable room to stand while typing and reading. [substeps] To find a good high-five when typing, try positioning your computer higher up than your computer screen. Ending2: If you can see the screen the whole time while doing this and you try to stand 5 feet away from it, you're standing too close. [title] Keep your angle of vision as high as possible. Ending3: [title] Locate the computer screen 4 or 5 inches below your eye level. [step] Ideally, you should look down at the computer screen at about a 15 to 20 degree angle. Ending4: You may straighten your arms out, trying to use only your feet. You may lie on a countertop, chair, or desk; however, the higher elevations provide greater protection for lenses than an arm stand.

Answer format: ending1/ending2/ending3/ending4