The main purpose of white blood cells is to combat infection. They are part of the body’s immune system and help to fight off harmful bacteria, viruses, and other foreign invaders. White blood cells are produced in the bone marrow and circulate in the blood and lymph fluid. There are several different types of white blood cells, each with its own specialized function. Some white blood cells, such as neutrophils and macrophages, engulf and destroy foreign invaders. Other white blood cells, such as lymphocytes, produce antibodies that help to neutralize toxins and bacteria. White blood cells are essential for maintaining good health and preventing disease.
Option A is incorrect because white blood cells do not carry nutrients. Nutrients are carried by blood plasma, which is the liquid part of blood.
Option B is correct. White blood cells combat infection by engulfing and destroying foreign invaders, producing antibodies, and releasing chemicals that help to fight infection.
Option C is incorrect because white blood cells do not carry oxygen. Oxygen is carried by red blood cells.
Option D is incorrect because white blood cells do not give strength. Strength is provided by muscles.