An insect bite may result in inflammation of that spot. This is triggered by the alarm chemicals such as

The cancer of the epithelial cells is called

Mark the correct statement

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

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 ?

Person $^{\prime}A^{\prime}$ cannot step out of his house. He has to spend his entire life in sterile isolation otherwise, he would quickly contract a fatal infection. This person has almost no effective immune system. This disease is also called as baby in a bubble syndrome. Identify the disease, this person $^{\prime} A ^{\prime}$ is suffering from