Correct Option
The correct option is Red blood cells.
Explanation
Human blood is a specialized connective tissue composed of a fluid matrix called plasma and formed elements, which include Red Blood Cells (RBCs), White Blood Cells (WBCs), and Platelets. Each component performs distinct physiological functions essential for homeostasis.
Option Analysis
- Red blood cells is Correct: Red Blood Cells (RBCs), or erythrocytes, are the most abundant cells in human blood. They contain haemoglobin, an iron-containing complex protein. Haemoglobin binds reversibly with oxygen to form oxyhaemoglobin, facilitating the transport of approximately 97% of oxygen from the lungs to the tissues.
- Plasma is Incorrect: Plasma is the viscous fluid constituting nearly 55% of blood volume. It primarily transports nutrients, hormones, and metabolic wastes. Only about 3% of oxygen is transported in a dissolved state through the plasma.
- Platelets is Incorrect: Platelets (thrombocytes) are cell fragments derived from megakaryocytes. Their primary function is blood coagulation (clotting) to prevent excessive bleeding during injury.
- White blood cells is Incorrect: White Blood Cells (WBCs), or leukocytes, are part of the immune system. They are responsible for defending the body against infections and foreign pathogens, not for oxygen transport.
Key Takeaway: Red Blood Cells are the primary agents for oxygen transport in the human body due to the presence of the respiratory pigment haemoglobin.