Please choose the correct ending to complete the given sentence: Health: [header] How to stretch your back using a foam roller [title] Arch your neck. [step] A foam roller can stretch out tight muscles and relieve any pain or tension you may have. It's especially great for stress-related soreness that accumulates in the neck and upper back.

Ending1: [substeps] Sit up straight and gently arch your back, keeping your shoulders in the same position and not arching your neck. If possible, place an arm or leg on top of your head if you want to stretch up the back of your neck. Ending2: [substeps] Your nose, forehead, and neck should not be arched too much when you stretch your neck muscles. Don't exercise too much or your neck might be sore. Ending3: [substeps] Hold a firm grip on the roller when you are stretching. Hold the tension in your neck for 5 seconds after clenching it. Ending4: Your upper back muscles are hearty and can usually take the pressure a foam roller provides. But your neck and lower back are more delicate and a foam roller may put too much pressure on it.

Answer format: ending1/ending2/ending3/ending4