Final answer:
The nurse should look for a rise in hemoglobin level (option C) to indicate that the client's medication, epoetin alfa, is having the desired therapeutic effect.
Step-by-step explanation:
The nurse should look for a rise in hemoglobin level (option C) to indicate that the client's medication, epoetin alfa, is having the desired therapeutic effect. Epoetin alfa is a medication that stimulates the production of red blood cells in the bone marrow. It is commonly used to treat anemia associated with chronic kidney disease. A rise in hemoglobin level indicates an increase in the number of red blood cells, which is the desired effect of the medication.