The first line of defence in the immune system is provided by

Options

A. skin and mucous membrane
B. inflammatory response
C. the complement system
D. none of these

Answer

A

Explanation

Skin and mucous membrane are the physical barriers that provide the first line of defence or the external defence. These barriers prevent the entry of microorganisms into the body. Outer tough layer of the skin, the stratumm corneum prevents the entry of bacteria and viruses. Mucus secreted by mucous membrane traps the microorganisms and immobilises them.