Eradication of smallpox has been possible due to the following facts except

In the given flow chart, the replication of retrovirus in a host cell is shown. Observe it carefully and fill up the blank $A, B$ and $C$

Identify the wrongly matched pair.

Women who consumed the drug thalidomide for relief from vomiting during early months of pregnancy gave birth to children with

‘Diphtheria' disease is connected with