Which of the following types of immunity is present at the time of birth and is a non-specific type of defense in the human body?

After maturation,in primary lymphoid organs,the lymphocytes migrate for interaction with antigens to secondary lymphoid organs like:
$A.$ thymus $B.$ bone marrow $C.$ spleen $D.$ lymph nodes $E.$ Peyer's patches
Choose the correct answer from the options given below:

In which organs do immature lymphocytes differentiate into antigen-sensitive lymphocytes?

Which of the following cells are associated with the immune system of the body?

Which of the following is a primary lymphoid organ?

What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis $B$ vaccine is produced.