When centrifuging a sample for hematocrit measurement, which layer will contain the most white blood cells?

The correct choice is the buffy coat, which is the thin layer that forms between the packed red blood cells at the bottom and the plasma at the top after centrifugation of a blood sample. The buffy coat contains the majority of the white blood cells, as well as platelets. During the centrifugation process, the blood components separate based on their density: the heaviest components (red blood cells) settle to the bottom, while the lighter components (plasma) remain at the top. The buffy coat, being a transitional layer, is where the white blood cells, which have a density between that of red blood cells and plasma, accumulate. This layer is crucial for various hematology assessments, including those related to immune function and the identification of certain blood disorders.