## Core Concept
Acute metabolic acidosis is a condition characterized by an excessive amount of acid in the body, leading to a decrease in blood pH. This condition arises due to an increase in the production of acidic substances or a decrease in the body's ability to remove acids. The body compensates for this imbalance through respiratory and renal mechanisms.

## Why the Correct Answer is Right
The correct answer involves understanding the primary compensatory mechanism for metabolic acidosis. In acute settings, the body initially compensates for metabolic acidosis through **hyperventilation**, which is mediated by the respiratory center in the brainstem. This increase in ventilation helps to blow off carbon dioxide (CO2), a volatile acid, thereby reducing the acidity of the blood. The equation for this compensatory mechanism can be represented as: **HCO3- (bicarbonate) + H+ (hydrogen ions) → CO2 + H2O**, with the CO2 being expelled through the lungs.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because while certain buffers can help mitigate acidosis, they are not the primary compensatory mechanism in acute settings.
- **Option B:** This option is incorrect because, although the kidneys do play a crucial role in acid-base balance by adjusting the excretion of hydrogen ions and bicarbonate reabsorption, their response is slower and more relevant in chronic compensation.
- **Option C:** This option might seem plausible but is not directly related to the immediate compensatory mechanism for acute metabolic acidosis.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that the respiratory compensation for metabolic acidosis can be estimated using the **Winter's formula**, which predicts the expected PaCO2 in the setting of metabolic acidosis: **PaCO2 = 1.2 * [HCO3-] + 15**. This helps in determining if the respiratory compensation is appropriate.

## Correct Answer Line
**Correct Answer: D.**