Passive immunity was discovered by

Which one of the following is found in the mouth of human beings

A new born baby who receives $IgA$ form its mother's milk develops

Which of the following set is of vector host

An additional risk of drug addiction, especially of heroin is

Identify the molecules $(A)$ and $(B)$ shown below and select the right option giving their source and use.

Molecule             $\to $         Source                  $\to $                Uses