What is the main physical barrier that prevents entry of microorganisms?

Step-by-step solution

Everyday we are exposed to a large number of infectious agents, however only a few of these exposures result in disease due to the fact that the body is able to defend itself from most of these foreign agents.Biotechnology is at the verge of making available newer and safer vaccines. Immunity is of two types: Innate immunity and Acquired immunity.Innate immunity is a non-specific type of defense that is present at birth and provides different types of barriers to prevent entry of foreign agents into the body. Acid