Smoking increases ______ content in blood and reduces the concentration of haembound oxygen. Fill the blank suitably

Female Anopheles is

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 ?

Drugs that cause malformation in embryo during pregnancy are called