An adult patient is demonstrating anaphylaxis from an insect sting. What is the nurse's priority intervention?
a. Benadryl (diphenhydramine) 50 mg intravenously
b. Oxygen at 3 liters via nasal cannula
c. Epinephrine 1:1000 0.5 mg subcutaneously
d. Normal saline at 150 mL/hr