Instructions: 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 get bigger chest muscles (pecs ) [title] Do push ups. [step] This often-neglected exercise focuses on building up your shoulder and upper chest muscles. Lie face-down on the floor and start with your hands about shoulder-width apart, with your legs stretched behind you. <sep> (A) Push your body up from the floor with your hands until your elbows are straight, then lower yourself until your arms reach a 90 degree bend. [substeps] Do 3 sets of 15 push-ups, or as many as you can before growing fatigued. (B) Your elbows should be bent at a 90 degree angle and your hands should rest squarely on your shoulders. Your feet should be planted firmly on the floor, but not so bent that they are bending below your hips. (C) Lift one leg up off the floor and bring it down to your ankle in a hard, controlled motion. Turn over on to your other side, keeping your torso balanced on your forearms. (D) Pull yourself up until your front chest is above the floor ( [title] Do arm press-ups. [step] The arms will do most of the weight-bearing (control) for you.
Output:
A