Final answer:
Mucus is a nonspecific barrier, antibodies and B cells are part of the adaptive immune system, and interferons are a nonspecific defense mechanism of the immune system.
Step-by-step explanation:
Mucus is a nonspecific barrier of the immune system. It helps to trap and flush out pathogens from the respiratory and gastrointestinal tracts, preventing them from entering the body.
Antibodies and B cells, on the other hand, are part of the adaptive immune system, which is the specific defense system that develops after exposure to a pathogen. Antibodies, produced by plasma cells, bind to specific antigens on pathogens to neutralize or mark them for destruction.
Interferons are signaling proteins that are released during viral infections to protect surrounding cells from viral replication, and they are also a nonspecific defense mechanism of the immune system.