Answer:
First line of defense ⇒ Includes mechanical barriers that prevent microorganisms from entering the body.
The presence of mechanical barriers such as the skin cover up the body and massively reduce the amount of microorganisms coming into the body.
Second line of defense ⇒ A complex defense that recognizes and reacts to specific organisms.
The body uses the protein presence on the organism to recognize that it is foreign as foreign cells have a different protein synthesis process than your own.
Third line of defense ⇒ Includes cells and process that help remove or neutralize organisms that have penetrated mechanical barriers.
Cells such as the Lymphocytes and Phagocytes work to neutralize the foreign organisms. Lymphocytes produce antibodies and Phagocytes ingest and neutralize them.