Examples of natural barriers include (mark all that apply) :

The natural barriers include biochemical, physical, and mechanical, as well as inflammation of the body.

Natural barriers and the immune system defend the body against the species that leads to infection. The natural barriers include the mucous membranes, skin, earwax, tears, stomach acid, and mucus. Also, the usual flow of urine washes out the microbes, which enter the urinary tract.