The correct answer is A- Raising and lowering the body to a 90° angle at the elbow with a flat back.
A push-up is a popular calisthenics exercise that involves raising and lowering you biceps and triceps to lift your entire body weight. Correct form and positioning is vital when performing a sit up in order to prevent unnecessary strain and injury. While performing a sit up, the correct form is raising and lowering the body to a ninety-degree angle at the elbow with a flat back.