## Core Concept
Acid-base disorders are conditions that occur when the body's acid-base balance is disrupted, leading to an excess of acid or base in the blood. The body maintains acid-base balance through buffer systems, respiratory adjustments, and renal compensation. Acid-base disorders can be classified into respiratory and metabolic disorders, each with acidosis (excess acid) or alkalosis (excess base).

## Why the Correct Answer is Right
The correct statement regarding acid-base disorders needs to be identified by evaluating each option. However, without specific details on options A, B, C, and D, we'll proceed with a general understanding. Typically, acid-base disorders involve:
- **Respiratory Acidosis**: Increased CO2 levels (hypercapnia) due to hypoventilation.
- **Respiratory Alkalosis**: Decreased CO2 levels (hypocapnia) due to hyperventilation.
- **Metabolic Acidosis**: Increased levels of acidic substances or decreased bicarbonate (HCO3-) levels.
- **Metabolic Alkalosis**: Increased bicarbonate (HCO3-) levels.

## Why Each Wrong Option is Incorrect
Given the lack of specific details for each option, let's consider common misconceptions:
- **Option A:** If it suggests that acid-base disorders are always simple (only one disorder present), it's incorrect because mixed acid-base disorders (more than one disorder) are common.
- **Option B:** If it implies that respiratory disorders are not compensated by renal mechanisms, it's incorrect because the kidneys can adjust HCO3- reabsorption or secretion to compensate for respiratory disorders.
- **Option C:** If it states that metabolic acidosis is always due to diabetic ketoacidosis, it's incorrect because metabolic acidosis can result from several causes, including lactic acidosis, renal failure, and ingestion of certain toxins.
- **Option D:** Without specifics, assume this could relate to a correct principle of acid-base balance.

## Clinical Pearl / High-Yield Fact
A key point to remember is the **anion gap**, which is crucial in evaluating metabolic acidosis. The anion gap is calculated as [Na+] - ([Cl-] + [HCO3-]). An increased anion gap (>12 mEq/L) suggests the presence of unmeasured anions, as seen in diabetic ketoacidosis, lactic acidosis, and renal failure. This is a high-yield fact for understanding and diagnosing acid-base disorders.

## Correct Answer: D.