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.

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.