**Core Concept**
The question tests the understanding of arterial blood gas (ABG) analysis and acid-base balance, specifically the interpretation of pH, pCO2, and HCO3 levels in diagnosing respiratory and metabolic disorders. **Acid-base balance** is crucial for maintaining homeostasis, and ABG analysis is a key diagnostic tool.

**Why the Correct Answer is Right**
Given the pH of 7.2, which is below the normal range (7.35-7.45), indicating **acidosis**, combined with a raised pCO2 (hypercapnia) and decreased HCO3 (bicarbonate), this points towards a **respiratory acidosis** with a possible metabolic component. The primary disorder is respiratory, as evidenced by the elevated pCO2, which suggests hypoventilation.

**Why Each Wrong Option is Incorrect**
**Option A:** Would typically represent a metabolic acidosis with no respiratory component, not matching the given ABG results.
**Option B:** Could represent a compensated respiratory alkalosis, which does not fit the acidotic state described.
**Option D:** Might suggest a purely metabolic cause, not accounting for the respiratory component indicated by the raised pCO2.

**Clinical Pearl / High-Yield Fact**
In interpreting ABG results, it's crucial to consider the pH, pCO2, and HCO3 together to determine the primary acid-base disorder and whether it's respiratory or metabolic in origin.

**Correct Answer:** D. Respiratory Acidosis.