Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to do a marching plank [title] Start with a forearm plank. [step] This is what most people consider to be the standard plank exercise, and it's a good place to start if you want to master the plank itself before moving on to more challenging variations. [substeps] You can get into position either by starting on all fours or by laying face down on a mat.

Ending1: Roll on your hands and knees so that your shins are off the ground, keeping your hips still. The handles of the planks should curve upward in one direction-behind your calves, toward your ankles. Ending2: [title] Have your hands out in front of you. [step] As you do this, the top knuckles of your right hand will be facing outward. Ending3: Keep your body close to the ground, butt up and forward with your buttocks tucked under you. Keep your shins parallel to the floor and your thighs parallel with the ground. Ending4: Line your elbows under your shoulders so that your upper body is supported by your forearms, and extend your legs behind you so that you are on your toes. Your body should be a straight line from your heels to the crown of your head.

Answer format: ending1/ending2/ending3/ending4