Which blood component is primarily responsible for carrying oxygen?

The primary role of red blood cells (RBCs), also known as erythrocytes, is to carry oxygen from the lungs to the tissues and organs throughout the body. This is accomplished through the specialized protein hemoglobin, which binds oxygen molecules in the lungs where oxygen concentration is high and releases it in areas where oxygen concentration is lower, such as tissues undergoing metabolic activity. The structure of red blood cells, being biconcave, increases their surface area for gas exchange, facilitating their efficiency in transporting oxygen.

In contrast, platelets are involved in blood clotting and do not play a role in oxygen transport. White blood cells are crucial for the immune response and help to fight infections but do not carry oxygen. Plasma is the liquid component of blood that carries cells, nutrients, hormones, and waste products, but it does not have the ability to transport oxygen on its own. Therefore, red blood cells are the key players in oxygen transport, making them the correct answer.