Which of the following is administered to increase the number of circulating red blood cells?

A. Nausea and vomiting: Nausea and vomiting can occur with epoetin alfa, but it's not the most common side effect.

B. Orthostatic hypotension: This is not a common side effect of epoetin alfa. Orthostatic hypotension is a decrease in blood pressure upon standing.

C. Hypertension: Epoetin alfa stimulates the production of red blood cells. When the red blood cell count increases too quickly, it can lead to increased blood pressure, which is the most common adverse effect.

D. Dizziness: Dizziness can occur with epoetin alfa, but it's less common than hypertension.

A. Vitamin K: Vitamin K is the antidote for warfarin, not heparin. Warfarin works by inhibiting the synthesis of vitamin K-dependent clotting factors in the liver. Therefore, vitamin K is used to reverse the effects of warfarin in cases of over-anticoagulation. It does not reverse the effects of heparin.

B. Deferoxamine: Deferoxamine is a chelating agent used to treat iron toxicity and aluminum overload. It is not indicated for reversing the effects of heparin.

C. Acetylcysteine: Acetylcysteine is used as an antidote for acetaminophen (paracetamol) overdose. It is not indicated for reversing the effects of heparin.

D. Protamine sulfate: This is the correct answer. Protamine sulfate is the antidote for heparin. It works by binding to heparin to form a stable complex, thereby neutralizing its anticoagulant effects. Protamine sulfate is commonly used in clinical practice to reverse the effects of heparin in situations such as hemorrhage or when rapid reversal of anticoagulation is needed, such as before surgery.