What is the function of white blood cells (WBC)?

White blood cells (WBC), also known as leukocytes, play a critical role in the immune system by defending the body against infections and foreign invaders. Their primary function is to identify, attack, and eliminate pathogens like bacteria, viruses, and other harmful organisms. They achieve this through various mechanisms, such as phagocytosis, where some WBCs engulf and digest pathogens, and the production of antibodies, which target specific invaders for destruction.

In contrast, other options represent functions of different components of the blood or bodily systems. For instance, transporting oxygen is the primary role of red blood cells (RBCs), while blood clot formation is mainly carried out by platelets and clotting factors. The statement about making up the majority of blood components refers to various blood constituents but does not pertain to the specific function of white blood cells. Understanding these distinctions highlights the unique and essential role WBCs play in maintaining health through their protective functions.