How Does the Skin Act as a Barrier to Microbial

How does the skin act as a barrier to microbial invasion?

A) It releases B cells and T cells to fight infections.
B) Dendritic cells patrol the skin's surface, producing secretions that inhibit microbe growth.
C) Sweat and sebaceous gland secretions inhibit bacterial growth.
D) Dead skin cells are packed with keratin, an antibacterial protein that punches holes in bacterial membranes.