A nurse is caring for a child who was admitted with suspected rheumatic fever. The provider prescribes an antistreptolysin O (ASO) titer. The child’s parent asks the nurse about the purpose of this test. Which of the following responses should the nurse make?

A. The ASO titer does not diagnose rheumatic fever directly; it indicates a prior streptococcal infection, which may have triggered rheumatic fever. B. This test is unrelated to aminoglycoside levels, which are measured to ensure therapeutic dosing and prevent toxicity. C. The ASO titer does not determine immunity; it detects antibodies produced in response to a recent infection. D. An elevated ASO titer confirms that the child had a recent streptococcal infection, which is important for supporting a diagnosis of rheumatic fever when combined with clinical findings.