A nurse is caring for a client who has HIV. Which of the following laboratory values is the nurse's priority?

A. This is within the normal range (150,000–400,000/mm³) and is not a priority concern. B. This is below 200 cells/mm³ and indicates the client has progressed to AIDS. A low CD4 count puts the client at high risk for opportunistic infections, making this the priority value to monitor. C. This confirms the presence of HIV but is not a current indicator of disease severity or immune function. D. This is at the lower limit of normal (5,000–10,000/mm³) and not immediately concerning compared to the critically low CD4 count.