Definition: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Input: [header] How to perform the medicine ball sit up exercise [title] Find a partner. [step] Sit facing them with your knees drawn up. Place your feet on top of theirs or vice versa. <sep> (A) Then, lie down so that you are face up. Make sure your lower back is touching the floor. (B) You can do this on a table, a bench, a carpeted floor or both, as long as you do not mind building contrast between them. [title] Place your hands at either end of your partners' legs. (C) Put on your hands, palms facing outwards. Then reach down in front of you, with your left elbow bent at a 90 degree angle. (D) [substeps] Don't clap or hit the soles of your feet to slow or smooth out the motion of the ball. Most regions of the body that are tender have the least soreness, as do those located around the abdomen.
Output:
A