Which of following is not a constitutent of physiological barrier in 'Innate immunity' ?

Mucus coating of the epithelium lining the respiratory tract

The correct option is 4 . Mucus coating of the epithelium lining the respiratory tract

Innate, or nonspecific, immunity is the defense system with which you were born. It protects you against all antigens. Innate immunity involves barriers that keep harmful materials from entering your body. These barriers form the first line of defense in the immune response. Physiological barriers include acid in stomach , saliva in mouth , tears from eyes .
Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts is an example of physical barrier.