Making anti-viral drugs is more difficult than making anti-bacterial medicines because

Choose the wrong statement:

Name two types of diseases caused by regularly breathing in the polluted air.

$A$ person has lost his power to fight infections. Name the disease the person is suffering from. State the pathogen and modes of transmission of this disease.

$(a)$ State the principle of immunisation. Name two diseases for which vaccines are available.
$(b)$ Mention two basic principles of prevention of infectious diseases.

Students of class $IX$ had to present a seminar on 'Dengue fever'. They wanted to introduce the disease by starting with:
$(a)$ Immediate causes of the diseases
$(b)$ Definition of infectious diseases
$(c)$ Pathogen causing dengue fever
$(d)$ Vector responsible for dengue microbe.
Can you help them to explain the above points? Give details.