What does hematocrit measure in a blood sample?

Hematocrit measures the percentage of red blood cells (RBCs) in a blood sample. This value is crucial for evaluating a person's blood composition and is often used to assess various medical conditions. A higher hematocrit may indicate dehydration or polycythemia, while a lower hematocrit can suggest anemia or other medical issues.

Understanding the role of red blood cells is essential, as they are responsible for transporting oxygen from the lungs to tissues and returning carbon dioxide for elimination. The hematocrit value is obtained by centrifuging a blood sample, which separates the components based on density: red blood cells settle at the bottom, while plasma remains at the top.

Other options do not measure what hematocrit assesses. The percentage of white blood cells relates to different health indicators, the volume of plasma provides a separate measure of blood composition, and blood pH level indicates acidity or alkalinity, unrelated to red blood cell volume. Thus, option C accurately reflects what hematocrit evaluates in a blood analysis.