Question

what role do white blood cells perform in a human body?
protect against pathogens
conducting electrical impulses
secreting enzymes
carrying oxygen

Explanation:

White blood cells are part of the immune system. Their main function is to protect the body from pathogens (such as bacteria, viruses, fungi). Conducting electrical impulses is a function of neurons. Secretion of enzymes is done by various glandular cells (e.g., in the digestive system). Carrying oxygen is the role of red blood cells (due to hemoglobin).

Answer:

protect against pathogens