What is the main function of the immune system?

The immune system's primary function is to protect the body against pathogens such as bacteria, viruses, fungi, and parasites. It does this through a complex network of cells, tissues, and organs that work together to identify and eliminate foreign invaders. This protective role is crucial for maintaining health and preventing infections. The immune response involves various components, including white blood cells, antibodies, and cytokines, all of which play specific roles in recognizing and combating pathogens.

While the other options touch on essential bodily functions—transporting nutrients, regulating body temperature, and facilitating digestion—none of these are the primary roles of the immune system. The immune system is uniquely dedicated to defending the body against diseases and infections, highlighting the critical importance of its function in overall health.