Arrange the following innate immune defenses in the correct order of their function in protecting the body from pathogens: A) Skin acts as a barrier, B) Pathogens encounter immune cells, C) Immune cells initiate response, D) Inflammation occurs at the site of infection.

The first line of defense is the skin, which blocks many pathogens from entering the body. Once a pathogen breaches that barrier, it meets immune cells that recognize it. Those immune cells then start the immune response, producing signals that recruit more cells. Finally, inflammation appears at the infection site, attracting even more cells and helping eliminate the threat. This sequence—skin barrier, pathogen encounter, immune cell activation, then inflammation—provides a layered, effective protection.