Feedback is used when the kidneys remove h+ ion from the blood when the ph of the blood becomes too acidic. positive or negative feedback

 Negative feedback

A buffer can be defined as a substance that help to resist or prevents a radical change in fluid pH by absorbing excess hydrogen or hydroxyl ions. Thus, the kidneys help control acid-base balance by excreting hydrogen ions and generating bicarbonate that helps maintain blood plasma pH within a normal range. The kidney is said to control pH by controlling the renal threshold of HCO3  . However, HCO3- level in the blood cannot rise without changes in levels of other anions or cations in the blood. To do so without effects on Na+, Cl- or other ions would defy electrical neutrality, i.e. the blood would become negatively charged and the urine positive.

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.