What role do white blood cells play in the body?

White blood cells are essential components of the immune system, designed to protect the body against infections, diseases, and foreign invaders. Their main role is to identify, target, and eliminate pathogens such as bacteria, viruses, and other harmful microorganisms. They achieve this through various mechanisms—some white blood cells, such as phagocytes, engulf and digest these invaders, while others, such as lymphocytes, are involved in producing antibodies and orchestrating the immune response.

White blood cells also play a significant role in developing immunity, providing long-term defense by remembering past infections and responding more rapidly upon subsequent exposures. This vital function demonstrates their crucial importance in maintaining overall health and fighting diseases, which aligns perfectly with the description given in the correct choice.

In contrast, red blood cells are responsible for transporting oxygen, hormones are produced primarily by glands within the endocrine system, and energy is typically stored in the form of glycogen in the liver and muscles. These functions highlight the distinct roles of various blood components and body systems, reinforcing the unique and imperative function of white blood cells in immune defense.