Final answer:
The injection of erythropoietin (Epogen) is meant to stimulate the patient's body to produce more red blood cells to address the oxygen-carrying deficit caused by aplastic anemia.
Step-by-step explanation:
The patient with aplastic anemia is asking about the purpose of the erythropoietin (Epogen) injection. The correct response that the nurse should provide is that the injection is intended to stimulate the body to produce more of its own red blood cells. Erythropoietin is a protein hormone secreted by the kidneys in response to low oxygen levels, and it triggers the bone marrow to produce red blood cells (RBCs). This increases the capacity of the blood to carry oxygen throughout the body, addressing the deficit caused by anemia.