What type of barrier is the mucus coating?

Match List-$I$ with List-$II$ :

List-$I$	List-$II$
$a$. Cellular barrier	$i$. Interferons
$b$. Cytokine barrier	$ii$. Mucus
$c$. Physical barrier	$iii$. Neutrophils
$d$. Physiological barrier	$iv$. $HCl$ in gastric juice

Choose the correct answer from the options given below:

Which of the following cells has the longest lifespan?

The mucus coating of the lining of the urogenital tract helps in trapping microorganisms entering our body. Which type of barrier is this?

Antibodies defend the body from the invading antigen by:

The binding of antibodies to antigens to produce a large insoluble complex is known as: