## Core Concept
The question tests the management of diabetic ketoacidosis (DKA), a serious complication of diabetes characterized by hyperglycemia, metabolic acidosis, and increased ketone bodies. The treatment involves fluid replacement, electrolyte replenishment, and insulin therapy to correct hyperglycemia and acidosis.

## Why the Correct Answer is Right
Insulin is the cornerstone of DKA management as it helps to decrease glucose production in the liver, increase glucose uptake by cells, and inhibit lipolysis, thereby reducing ketone body formation. The most effective and commonly used insulin regimen in DKA is a continuous intravenous infusion of regular insulin. This approach allows for tight control of blood glucose levels and helps to correct acidosis.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because, although fluid replacement is a crucial initial step in DKA management, it does not directly address the hyperglycemia and ketoacidosis.
* **Option B:** This option is incorrect as it might represent another treatment aspect, but without specifics, it's clear that insulin directly addresses the pathophysiology of DKA.
* **Option D:** This option is incorrect because, while monitoring and supportive care are vital, they do not directly treat the hyperglycemia and ketoacidosis.

## Clinical Pearl / High-Yield Fact
A key point to remember is that in DKA, **intravenous insulin** is the drug of choice because it allows for rapid control of blood glucose and ketoacidosis. Also, remember that **potassium** levels should be monitored and supplemented if necessary, as insulin can drive potassium into cells, potentially worsening hypokalemia.

## Correct Answer: .