**Core Concept**
High-resolution computed tomography (HRCT) is the investigation of choice for interstitial lung disease (ILD) due to its ability to provide detailed images of the lung parenchyma, allowing for the detection of subtle abnormalities and patterns characteristic of specific ILD entities.

**Why the Correct Answer is Right**
HRCT is superior to traditional chest radiography and other imaging modalities in the evaluation of ILD because it can depict the distribution and extent of lung involvement, including the presence of ground-glass opacification, honeycombing, and reticular patterns. The detailed images obtained with HRCT enable accurate diagnosis and assessment of disease severity, which is essential for guiding management and predicting prognosis. In addition, HRCT can be performed with contrast enhancement to evaluate the pulmonary vasculature and detect complications such as pulmonary embolism.

**Why Each Wrong Option is Incorrect**
* **Option B:** Chest radiography is not sensitive enough to detect the subtle abnormalities characteristic of ILD, and it is often normal in early disease or in patients with mild disease.
* **Option C:** Magnetic resonance imaging (MRI) is not typically used for the evaluation of ILD, as it is not as sensitive as HRCT in detecting lung parenchymal abnormalities.
* **Option D:** Positron emission tomography (PET) is not the investigation of choice for ILD, as it is primarily used for evaluating malignancy and infection.

**Clinical Pearl / High-Yield Fact**
When interpreting HRCT images of ILD, it is essential to recognize the characteristic patterns and distribution of abnormalities, as well as the presence of any associated complications or comorbidities.

**Correct Answer:** A. High-resolution computed tomography (HRCT)