23. Which of the following statements regarding cells of immune system is correct? (1) Cells in the innate immune system use Pattern recognition receptors (PRRs) to recognize molecular structures that are produced by microbial pathogens. (2) Dendritic cells, macrophages, monocytes, neutrophils and epithelial cells, all belong to the innate immune system. (3) Innate immune cells are also important mediators in lymphoid organ development and the activation of the adaptive immune system. (4) Helper T cells only recognize antigens coupled to Class I MHC molecules, while Killer T cells and regulatory T cells only recognize antigens coupled Class II MHC molecules. (5) Helper T cells regulate both the innate and adaptive immune responses and help determine which immune responses the body makes to a particular pathogen. (A) (2), (3), (4) and (5) (B) (1), (2), (3) and (4) (C) (1), (2), (4) and (5) (D) (1), (3), (4) and (5) (E) (1), (2), (3) and (5)