Bare lymphocyte syndrome type II is caused by the inability to express MHC class II molecules. Which of the following statements is consistent with this abnormality?

A) T-cell co-receptor CD4 is unable to signal through the protein kinase Lck, leading to halted CD4 expression in developing T cells.
B) B-cell co-receptor CD19 is unable to bind to IgM, leading to impaired B-cell activation.
C) Macrophages lose their ability to phagocytose pathogens due to decreased expression of Toll-like receptors.
D) NK cells lose their cytotoxic function due to impaired expression of perforin.