Which of the following is related to humoral immunity?

Match the following columns:

Column-$I$	Column-$II$
$(A)$ Physical barriers	$(1)$ Interferon
$(B)$ Physiological barriers	$(2)$ Leukocytes
$(C)$ Cellular barriers	$(3)$ Tears
$(D)$ Cytokine barriers	$(4)$ Skin

The letter $T$ in $T$-lymphocyte refers to:

What is an antibody?

Which of the following immune responses is responsible for the rejection of a kidney graft?

Assertion $A$: Innate immunity consists of various barriers. Reason $R$: Exposure to a pathogen is required for the stimulation of innate immunity. Which option is correct for Assertion $A$ and Reason $R$?