$NK$ cells are which type of cells?

$A$ person who met with a road accident is likely to develop tetanus. He is immunized by administering:

Read the following statements and choose the correct set of statements $:$
$(a)$ Cell-mediated immune response is responsible for the graft rejection.
$(b)$ Grafts from just any source $-$ an animal,another primate,or any human beings can be made since the grafts would be accepted sooner or later.
$(c)$ The organs cannot be taken from just anybody for transplant.
$(d)$ Tissue matching,blood group matching are essential before undertaking any graft/transplant.
Choose the correct answer from the options given below $:$

Which type of antibody is produced in the body against the body's own cells in rheumatoid arthritis?

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

Perforin is secreted by which of the following cells to prevent the effect of microbes?