Given below are two statements. One is labelled Assertion (A) and the other is labelled Reason (R). 

Assertion (A): Saliva functions as a natural defense mechanism in the innate immune system.

Reason (R): It is a physiological barrier that prevents microbial growth.

In light of the above statements, choose the correct answer from the options given below. 

Both (A) and (R) are true and (R) is the correct explanation of (A).

Saliva functions as a natural defense mechanism in the innate immune system. It contains antimicrobial proteins (lysozymes) and enzymes that help to protect against infections and contribute to the body’s first line of defense.

Saliva acts as a physiological barrier by inhibiting microbial growth. It contains various components like lysozymes, immunoglobulins, and other substances that help to neutralise and flush out microbes from the mouth.