Except skin, other physical barriers which also helps to prevent the entry of the microorganisms are
$I.$ mucus coating of the epithelium lining the respiratory
$II.$ gastrointestinal tracts
$III.$ urogenital tracts
Choose the correct option
$I\; and \;II$
$I \;and\; III$
$II\; and\; III$
$I, II\;and\; III$
Full forms : $RBC$
$A$ : It is considered advantageous to give the polio vaccine orally.
$R$ : It prevents reinfection by causing intestinal immunity
Antibodies fight against