A. Both decrease: While bicarbonate decreases, the anion gap specifically increases due to the accumulation of ketoacids. B. Both increase: Bicarbonate is consumed to buffer the acid, so its levels must drop. C. Anion gap decreases, HCO3 increases: This describes a state of alkalosis or recovery, the opposite of DKA. D. Anion gap increases, HCO3 decreases: In DKA, acidic ketone bodies (anions) accumulate. This widens the "gap" between measured cations and anions. Bicarbonate (HCO3-) is used up trying to neutralize these acids, leading to low levels.