A macrophage phagocytoses a bacterium and processes its antigens. Which of the following molecules will present these processed bacterial antigens to CD4+ T lymphocytes?

✓ Correct Answer: Option B

Macrophages are antigen-presenting cells that phagocytose exogenous antigens (like those from bacteria). They process these antigens and present them on MHC class II molecules to activate CD4+ (helper) T lymphocytes.