Final answer:
The treatment of diabetic ketoacidosis with insulin can cause a shift of potassium from the extracellular fluid into the cells, resulting in hypokalemia.
Step-by-step explanation:
The scenario described involves the treatment of diabetic ketoacidosis with insulin. During ketoacidosis, individuals with diabetes experience increased levels of ketone bodies due to the utilization of fats for energy, as glucose is not properly taken up by cells. This leads to acidification of the blood. When insulin is used as a treatment, it promotes the uptake of glucose into cells, which also facilitates the shifting of potassium (K+) from the extracellular fluid (ECF) into the cells. Consequently, this can cause a decrease in the levels of potassium in the blood and interstitial fluid, a condition known as hypokalemia. Hence, the appropriate answer to the sequence of events described is 'a. Hypokalemia'.