Read the following statements regarding the barriers of innate immunity: (A) Mucus coating of the epithelium lining the respiratory tract is a physiological barrier. (B) Acid in the stomach and saliva in the mouth are examples of physical barriers. (C) Natural killer cells in the blood are a type of lymphocyte that act as cellular barriers. (D) Interferons are proteins secreted by bacteria-infected cells to protect n

Step-by-step solution

Statement (A) is incorrect because the mucus coating of the epithelium lining the respiratory, gastrointestinal, and urogenital tracts is a physical barrier, not a physiological barrier. Statement (B) is incorrect because acid in the stomach, saliva in the mouth, and tears from the eyes are physiological barriers, not physical barriers. Statement (C) is correct as Natural killer cells are a type of lymphocyte present in the blood that function as cellular barriers of innate immunity. Statement (D) is incorrect beca