Which of the following correctly lists the four main components of blood?

• A. Plasma, hemoglobin, hematocrit, and antibodies
• B. Plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
• C. Interstitial fluid, red blood cells, white blood cells, and albumin
• D. Serum, lymphocytes, macrophages, and fibrin

Answer: (B)

Verified step by step guidance

1. Step 1: Understand that blood is a connective tissue composed of both liquid and cellular components.
2. Step 2: Identify the liquid portion of blood, which is called plasma. Plasma contains water, proteins, nutrients, hormones, and waste products.
3. Step 3: Recognize the three main types of cellular components suspended in plasma: red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
4. Step 4: Note that hemoglobin is a protein inside red blood cells, hematocrit is a measurement of the proportion of red blood cells in blood, and antibodies are proteins produced by certain white blood cells; these are not main components themselves but parts or functions related to the components.
5. Step 5: Conclude that the four main components of blood are plasma, red blood cells, white blood cells, and platelets, as these represent the fundamental structural elements of blood.