Which of the following heart sounds, while not considered "normal" in a young person who is not an athlete, can be a normal finding in the elderly?

A. S4: An S4 heart sound is caused by atrial contraction against a stiff, noncompliant ventricle. Age-related ventricular stiffening makes this finding relatively common in older adults and it may be present without acute pathology. It is often heard in patients with long-standing hypertension or age-related diastolic changes. B. S3: An S3 heart sound reflects rapid ventricular filling and increased volume states. In older adults, it is associated with heart failure or volume overload rather than a normal physiologic finding. It is considered abnormal outside of children, young adults, or well-trained athletes. C. S2: S2 represents closure of the aortic and pulmonic valves and is a normal heart sound in all age groups. While normal, it is not the specific age-related finding being assessed in this question. D. S1: S1 reflects closure of the mitral and tricuspid valves and is normally present in all individuals. Its presence does not distinguish normal aging-related cardiac changes.