The inability to distinguish between self cells and non-self cells may lead to

Assertion $(A)$: Antigen can be easily recognized because it has antigenic determinants.
Reason $(R)$: The recognition ability is innate.

Assertion : Organ transplantation patients are given immunosuppressive drugs.
Reason : Transplanted tissue has antigens which stimulate the specific immune response of the recipient.

The protein that possesses the property of immunity is .........

The immunity developed by a child after an attack of measles is . . . . . . immunity.

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