**Core Concept**
The question is testing the role of transbronchial biopsy in diagnosing pulmonary fibrosis, a condition characterized by the scarring of lung tissue, leading to a restrictive defect in pulmonary function. Transbronchial biopsy is a minimally invasive procedure that involves obtaining a small tissue sample from the lung through a bronchoscope.

**Why the Correct Answer is Right**
Transbronchial biopsy is useful in diagnosing pulmonary fibrosis by providing a histopathological examination of the lung tissue. The biopsy can demonstrate the characteristic features of pulmonary fibrosis, including the presence of fibrotic lesions, honeycombing, and architectural distortion. The biopsy can also help to differentiate between various types of interstitial lung diseases, such as idiopathic pulmonary fibrosis, sarcoidosis, and pulmonary lymphangitic carcinomatosis. The histopathological findings can be correlated with the imaging findings, such as those seen on high-resolution CT, to confirm the diagnosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Transbronchial biopsy is not typically used to diagnose pulmonary fibrosis because it is primarily a diagnostic tool for evaluating malignancies or infections.

**Option B:** Transbronchial biopsy is not the most sensitive or specific diagnostic tool for pulmonary fibrosis, as other imaging modalities, such as high-resolution CT, can provide more detailed information about the extent and distribution of lung fibrosis.

**Option C:** Transbronchial biopsy is not used to treat pulmonary fibrosis, which is a chronic and irreversible condition.

**Clinical Pearl / High-Yield Fact**
The histopathological features of pulmonary fibrosis can be remembered using the mnemonic "HONEYCOMB": Honeycombing, Obliterative bronchiolitis, Nodular lesions, Eosinophilic pneumonia, Yellowing of lung tissue, Collapse of lung tissue, and Bronchiectasis.

**Correct Answer:** C. Obtaining a tissue diagnosis to confirm pulmonary fibrosis.