A 65-year-old man with chronic obstructive pulmonary disease (COPD) is hospitalized with pneumonia. His blood tests show elevated IgG levels directed against the pathogen. What is the function of IgG in this context?

• A. Binding to mast cells to trigger histamine release
• B. Neutralization of the pathogen and opsonization
• C. Triggering the classical complement pathway
• D. Both B and C

Answer: (D)