Final Answer:
Dorsiflexion refers to the movement of pulling the foot upward towards the shin, decreasing the angle between the foot and the shin. Option A, "stand back on your heels," correctly describes dorsiflexion.
Step-by-step explanation:
When you dorsiflex your foot, you bring the top of your foot closer to the front of your leg, allowing you to shift your weight backward and stand on your heels.
Options B and C are not related to dorsiflexion. Standing on the lateral margins of the feet (option B) is more associated with inversion, and pointing your toes medially (option C) is related to inversion or plantarflexion. Option D, "stand on your toes," is associated with plantarflexion, the opposite movement of dorsiflexion.
Option A is the answer.