Please choose the correct ending to complete the given sentence: Uncategorized: [header] How to build lower abs [title] Start on your back with your knees bent. [step] Lie with your feet flat on the floor and palms facing down. For extra support, spread your arms out straight to each side.

Ending1: [substeps] Lie on a mat or thick towel to cushion your head, back, and hips. [title] Raise your legs and bring your knees toward your chest. Ending2: [substeps] To keep your back and knees from causing undue pressure on your pelvis, do this exercise before going to bed. [title] Get into a 90% lie position. Ending3: As you reach your knees up to your ears, lean back in a rocking way. Like a good workout, you'll strengthen your abs. Ending4: You may make sure to use an elastic pad on your back. [substeps] Your feet should be almost touching the floor next to you.

Answer format: ending1/ending2/ending3/ending4