I really l need help with this question

A

Explanation:

The skin, mucous membranes, and endothelia throughout the body serve as physical barriers that prevent microbes from reaching potential sites of infection. Tight cell junctions in these tissues prevent microbes from passing through.

Hope this helps:)

i am going to put the answers in order i dint feel like typing it out so yeah

a

d

c

b

b

b

a

d

a

b

c

c

c

b

d

first one is the correct answer