Write the next sentence in this paragraph:

How to do a butterfly stretch
Exercise.
The butterfly stretch is useful as a cooling down stretch. Before doing it, you will want to have done at least five to ten minutes of light to moderate cardio activity, such as walking or cycling.

Pick your answer from: (a). Get on all fours with your knees bent and arms straight. Keep your knees in or out of alignment with your body. (b). Good cardio activities include jogging, swimming, and ballet. If you don't feel like you can do high intensity exercises, yoga, or light weight exercises will likely provide no such benefits. (c). Stretches like this before you are warmed up can result in an injury. Sit on the floor with both legs straight out in front of you. (d). Doing this will also help strengthen and firm your abdominal muscles, which can make your workout easier. Cycling is an exercise that helps stretch your core, shoulders, and back, while also encouraging your muscles to contract.
(c).