Which of the following is a major component of plasma?

• A. Water, proteins, electrolytes, nutrients, hormones.
• B. Erythrocytes, leukocytes, platelets.
• C. Glucose, insulin, glucagon.
• D. Oxygen, carbon dioxide, nitrogen.

Answer: (A)

Plasma is the liquid portion of blood, so its biggest component is water. But plasma isn’t just water—it's water with dissolved substances that are carried to and from tissues. The major solutes include plasma proteins (like albumin, globulins, and fibrinogen), electrolytes (such as sodium, potassium, bicarbonate, and chloride), nutrients (glucose, amino acids, lipids), and hormones. This combination allows plasma to transport nutrients and wastes, maintain osmotic balance, and support various regulatory processes. The other choices point to cellular elements (blood cells) or to specific gases or metabolites, which are present in plasma but do not constitute its major component. So the best description is water with dissolved proteins, electrolytes, nutrients, and hormones.