Final answer:
The correct instruction to give to a patient for administering epinephrine is to inject it into the thigh muscle.
Step-by-step explanation:
The correct instruction to give to a patient whom you are about to assist with administering epinephrine is option C: I am going to inject medication into your thigh. Epinephrine is administered through an injection into the thigh muscle, usually using an auto-injector device like an EpiPen®. This allows the epinephrine to be rapidly delivered into the bloodstream to counteract the life-threatening allergic reaction.