Please choose the correct ending to complete the given sentence: Health: [header] How to help bad knees with yoga [title] Practice mountain pose to improve your alignment and get you warmed up. [step] This is perhaps the most basic standing pose in yoga, and will strengthen your thighs and knees. This pose is also good for people suffering from knee osteoarthritis.

Ending1: [substeps] To begin, first, lie on your back with your knees bent. Raise your left hand up and then press your right heel into the mat, creating a gentle lift. Ending2: [substeps] To start, start with a smooth and sturdy mat, such as an old sheet or a piece of mattress. You need a mat that's thicker than 3-4 feet (0.91-0.91 m). Ending3: [substeps] Stand straight with your feet together on a yoga mat or exercise mat. Make sure your big toes are touching and your heels are slightly apart. Ending4: [substeps] Put your feet as wide apart as you can without touching the ground. Bring your feet hip-width apart and twist your body as you arch your back.

Answer format: ending1/ending2/ending3/ending4