What are the main components of blood?

The main components of blood are indeed red blood cells, white blood cells, and plasma. Red blood cells are responsible for transporting oxygen from the lungs to the body's tissues and carrying carbon dioxide back to the lungs for exhalation. White blood cells play a crucial role in the immune system, helping the body fight off infections and diseases. Plasma is the liquid component of blood, making up about 55% of its total volume; it primarily consists of water, electrolytes, proteins, and nutrients, and it serves as a medium for transporting cells, nutrients, hormones, and waste products throughout the body.

Other options include components that are not part of blood. For example, platelets play a role in blood clotting but are not mentioned alongside the primary blood components in the correct context. Options including nerves, connective tissues, hormones, and enzymes pertain to different physiological systems and categories, highlighting the importance of understanding the specific functions and definitions of blood components in human physiology.