Answer:
C. Shift his weight from the back foot to the front foot while striking the ball
Step-by-step explanation:
By shifting his weight forward, he can transfer the energy generated from his legs and torso into the ball, resulting in a faster serve. Holding the racquet further away from his body or with his non-dominant hand is unlikely to have a significant impact on weight transfer. Shifting his weight from the front foot to the back foot while striking the ball would actually decrease the power and speed of the serve.