The most numerous cells in the blood are erythrocytes. Which option best describes this statement?

• A. Erythrocytes
• B. Leukocytes
• C. Platelets
• D. Plasma

Answer: (A)

The main idea here is how blood is composed and which components are most numerous. Erythrocytes, or red blood cells, are the most abundant formed element in blood. They are produced in large numbers to meet the body’s constant need to transport oxygen, and you typically have about 4–6 million erythrocytes per microliter of blood. In contrast, leukocytes (white blood cells) are immune cells present in far fewer numbers, and platelets are cell fragments involved in clotting, also far less numerous than red blood cells. Plasma isn’t a cell at all; it’s the liquid component of blood. So describing the statement with erythrocytes is correct because red blood cells are indeed the most numerous cells in the blood.