Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to do a knee raise with an exercise ball [title] Take your exercise ball and place it where surrounding objects won't obstruct your exercise. [title] Sit down on the exercise ball with your legs in front of you, knees bent and feet on the ground. [step] Walk yourself forward slightly if you're not comfortable, but don't fully lean back against the ball.

Ending1: Then gently lower yourself to a seated position. [title] Bend over the ball so that your knees are at a 90 degree angle to the ground. Ending2: Point your arms straight out (so that your wrists, elbows, and shoulders are aligned). Inhale and you should be in a neutral position. Ending3: Squat down until your thighs are in line with the bottom of the ball, and grasp the lower ankle as tightly as you can. Move slowly and avoid straining yourself to get up. Ending4: [title] Reach down to your knee, but remain in the air. [step] Hold this for 5 seconds before releasing.

Answer format: ending1/ending2/ending3/ending4