Final answer:
A hematocrit reading of 37 signifies that red blood cells (RBCs) account for 37% of the total blood volume, which means the remaining 63% is mostly plasma. The correct answer is option b.
Step-by-step explanation:
A hematocrit reading of 37 indicates that RBCs (red blood cells) account for 37% of the total blood volume. A hematocrit test measures the percentage of erythrocytes, or RBCs, in a sample of centrifuged blood. The heavier erythrocytes settle at the bottom of the hematocrit tube, and the remainder of the blood is composed of plasma and a thin layer referred to as the buffy coat, which contains leukocytes (white blood cells) and platelets.
Option b is the correct answer: b. RBCs account for 37% of the total blood volume. It's important to note that the hematocrit value can vary notably based on gender and other factors, with normal values ranging from 36 to 50 percent. The percentage of blood that is not erythrocytes typically constitutes the plasma volume. Given the hematocrit value of 37, we can imply that the approximate percentage of plasma in the blood would be the remaining portion, roughly 63% (100 minus 37).
While options a, c, and d mention hemoglobin levels, white blood cells, and an incorrect percentage of RBCs respectively, they are not correct in the context of what a hematocrit value signifies.