Answer: A- Raising and lowering the body to a 90° angle at the elbow with a flat back.
Step-by-step explanation:
A push up is a exercise in which the hands are pressed at the floor and shoulders are kept wider and the entire pressure is kept over the pectoral muscles of the body. In this practice the entire weight of the body is over the biceps and triceps. There should be a ninety degree angle between the forearm and upper arm and also there should be a ninety degree angle between the back and elbow. The back should be kept horizontal to the ground and it should be kept straight without any curvature.