This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Which of the following aid in the killing of intracellular bacteria? 
Select and explain. 
A. Histamine, B. Interleukin-2, C. Catalase, D. Lysozyme
D: Lysozyme
Answer: D: Lysozyme 
Explanation: Bacteria that are phagocytosed by macrophages are kept in membrane-bound vacuoles called phagosomes. A phagosome will fuse with a lysosome, which contains many degradative enzymes, including lysozyme.