Which of the following is the correct representation of an antibody molecule?

Assertion $A$: Cell-mediated immunity is responsible for the rejection of organ transplants. Reason $R$: The body's immune system has the ability to differentiate between self and non-self. Which option is correct for Assertion $A$ and Reason $R$?

Transplantation of tissues/organs often fails due to non-acceptance by the patient's body. Which type of immune response is responsible for such rejections?

Acquired immunity is due to

Which of the following is not present in the structure of an antibody?

Which cells are responsible for the production of antibodies?