$A$ patient rejects a transplanted kidney because of ..........

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

In the given figure,the part labeled as '$a$' represents:

Plasma cells are .....

Fill in the blanks: Our body, when it encounters a pathogen for the first time, produces a response called . . . . . . $a$ . . . . . . response, which is of . . . . . . $b$ . . . . . . intensity. Subsequent encounters with the same pathogen elicit a . . . . . . $c$ . . . . . . intensified . . . . . . $d$ . . . . . . response.

When ready-made antibodies are directly given to protect the body against foreign agents,it is called . . . . . . .