The answer is letter D.
A stretch should be ideally held between 10 to 30 seconds to inhibit proper muscle lengthening and shortening of fibers. Anything shorter than this duration would lead to no benefit of the stretch, while anything longer can lead to injuries. Stretching is an important component in a safe rainting program of an individual that is set to reach a specific fitness goal. There are two types of stretches and these are active stretches (done before a workout) and passive stretches (done after a workout).