Why is an antibody molecule represented as $H_2I_2$ ?

For an organ transplant, it is an advantage to have an identical twin. Why ?

Given below are two statements :

Statement $I:$Autoimmune disorder is a condition where body defense mechanism recognizes its own cells as foreign bodies.

Statement $II:$Rheumatoid arthritis is a condition where body does not attack self cells.

In the light of the above statements, choose the most appropriate answer from the options given below:

Consider the following statements

$I.$ People should get vaccination to avoid infection

$II.$ Vaccination is available against polio, cholera, typhoid, tuberculosis and many othe disease

$III.$ Eradication of vectors are necessary in diseases like malaria and filariasis

$IV. $ Dengue and chikengunya, both are spread by Culex mosquitoes

Which of the statements given above are correct?

Interferon is

Assertion : Interferons are effective against viruses.

Reason : Proteins which can be synthesized only by genetic engineering are effective against viruses.