Identify $X$ and $Y$ from the following structure
$X$ Antigen binding site, $Y$ -Heavy chain
$X$ light chain, $Y$ -Heavy chain
$X$ light chain, $Y$ -Antibody
$X$ Antigen binding site, $Y$ -Light chain
The causative agent of tuberculosis is
Filaria, malaria, dengue fever, sleeping sickness, yellow fever are transmitted by
Vaccination protects a person from disease because it
An additional risk of drug addiction, especially of heroin is
Full forms : $CO$