When a person dies after stung by bee followed by the administration of penicillin, death may be due to

In the given flow diagram, the replication of retrovirus in a host is shown. Observe and answer the following questions.

$(a)$ Fill in $(A)$ and $(B)$

$(b)$ Why is the virus called retrovirus ?

$(c)$ Can the infected cell survive while viruses are being replicated and released ?

Vaccines are prepared from immune

Non-specific host defence that exists prior to the exposure to an antigen is called

Symptoms of oedema is

First triple antigen vaccination is given to the child at the age of