Problem: An 85-year-old man comes to the office because he has had lower energy levels and increased fatigue with his usual activities. History includes longstanding stable chronic kidney disease, stage 4. Laboratory findings indicate stable renal function. Hemoglobin is 8.5 g/dL, with evidence of microcytosis. There is iron deficiency, with iron saturation at 8% and ferritin level at 85 ng/mL. Which one of the following is the most appropriate next step for managing this patient's anemia secondary to chronic kidney disease? Group of answer choices Blood transfusion Course of intravenous iron Initiation of oral iron supplements Initiation of erythropoietin