Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body. Which barrier of innate immunity is this?

Physical barriers  include mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body.Physiological - Acid in stomachCellular - WBCsCytokine - Interferons