Interferons are produced in response to

Acquired immunity is due to

In the case of a snakebite, the patient is injected with preformed antibodies against the snake venom. This type of immunity is called.........

Identify the cells that assist $B$-lymphocytes in the production of antibodies.

Which type of immunity is characterized by memory?

Match the Column-$I$ with Column-$II$ and select the correct option.

Column-$I$	Column-$II$
$1$. Cellular barrier	$A$. Saliva in the mouth
$2$. Physiological barrier	$B$. Interferons
$3$. Cytokine barrier	$C$. Natural killer (type of lymphocyte)
$4$. Physical barrier	$D$. Mucus coating of the respiratory tract