The Physician Has Prescribed Isometric Exercises for a Patient

The physician has prescribed isometric exercises for a patient.The patient asks the nurse how these exercises work.The nurse uses an example to explain the physiology of isometric exercises,which is:

A) flexing the lower arm while trying to straighten it with the other hand.
B) pulling the knees up to chest with the arms.
C) forcefully flexing the neck to make the chin touch the chest.
D) flexing the toes up toward the head while lying flat.