B, don't move your shoulders, just try to stretch your neck forward for 6 seconds, then slowly pull your chin down to your neck as far as possible, keep this action for 6 seconds, then relax and repeat it many times.
C sticking out your tongue is an ideal way to keep the skin loose between your chin and neck, which can prevent the formation of your chin and reduce the formation of your chin.
D holding your tongue against the teeth of the chin can also tighten the skin of the neck and dilute the double chin.