In addition to buffering, how does the body of a patient in diabetic ketoacidosis try to correct the acid-base imbalance?
a. The kidneys reabsorb all filtered H*
b. The kidneys excrete bicarbonate (HCO, ).
c. The rate and depth of respirations increase (Kussmaul respirations).
d. The kidneys shut down to conserve water.

In diabetic ketoacidosis (DKA) -- which typically occurs in patients with type 1 diabetes mellitus -- the patient's pancreas does not secrete sufficient amounts of insulin, if it secretes any at all, which means the glucose (blood sugar) within the patient's blood cannot be properly metabolized for the body to have its main energy source. The patient's body consequently takes this as a signal that there is not enough glucose and begins a process called ketosis. During ketosis, the patient's body will begin to breakdown fats to produce fatty acids in order to turn them into glucose. In turn, ketosis creates a waste product known as ketone bodies (ketones), which are acids. Thus, the acidity of the patient's blood increases.

The patient's pH will likely be lower than the expected range of 7.35 to 7.45, reflecting the acidotic state. To correct such, the patient's body will likely begin its attempts to compensate and prevent the acidity from worsening:

The kidneys may conserve bicarbonate (HCO₃-) because it is basic and having higher concentrations can help balance the acidity of the blood. This is the buffering the question is referring to.
The body may attempt to excrete excess hydrogen because the more hydrogen ions circulating unbonded within the blood, the lower the pH, which means more acidic blood.
The kidneys will increase its excretion of urine to try and offload ketones via this route; polyuria is a characteristic of both hyperglycemia and DKA. And,
The lungs will hyperventilate at a rate and depth known as Kussmaul respirations (deep and fast breaths) to decrease carbon dioxide concentrations; carbon dioxide in the presence of water within the blood quickly converts to carbonic acid, which would lower the pH.

So in short, patients in DKA will try to correct the acid-base imbalance by increasing the rate and depth of respirations (Kussmaul respirations), option C.