The correct answer is C. Lysozyme is an enzyme found in saliva and tears that can kill pathogens by attacking their outer membranes. Antibodies, T-cells, and B-cells are all part of the adaptive immune system.

The correct answer is A. White blood cells that target “self” attack the body’s own tissues. For example, in type 1 diabetes, the immune system wrongly attacks the pancreas, the organ responsible for making insulin.

The correct answer is A. The adaptive immune system gets its name from its ability to remember the pathogens it encounters. This phenomenon, called immunological memory, is a key part of how vaccines work.

The correct answer is D. Immunodeficiency disorders are a category of diseases, either genetic or caused by external factors, that make people highly susceptible to infection.

The correct answer is B. Bacterial, viral, and fungal infections are all common insults that cause sepsis.