Which three are potential portals of entry for pathogens?

The selection highlights three significant portals of entry for pathogens: the skin, respiratory tract, and bloodstream. Each of these areas represents a potential entry point through which infectious agents can invade the body.

The skin serves as the body's first line of defense, but when it's compromised—through cuts, abrasions, or other skin conditions—it can allow pathogens to enter directly. The respiratory tract is another common portal, as many pathogens are transmitted via inhalation of contaminated droplets or aerosols. The bloodstream is particularly critical since it can facilitate the spread of pathogens throughout the body, allowing them to infect various tissues and organs.

Understanding these portals of entry is vital for implementing effective infection control measures, as they outline where protective strategies need to be placed to prevent infections. Other combinations offered do include relevant parts of the body, but they either miss key points or mix in areas that do not primarily serve as portals of pathogen entry.