Which of the following plays a role in preventing the entry of microorganisms into the body?

• A
  $HCl$ acid,saliva in the mouth,tears from the eyes
• B
  $PMNL$,monocytes,$NK$ cells
• C
  Epithelial lining of the respiratory,gastrointestinal,and urogenital tracts
• D
  Interferons,antibodies,$B$-cells,$T$-cells