**Core Concept**
Sarcoidosis is a systemic granulomatous disease characterized by the formation of non-caseating granulomas in various organs, including the lungs. The Scadding system is a classification of pulmonary sarcoidosis based on chest radiography findings, ranging from Stage 0 (normal chest X-ray) to Stage IV (fibrosis).

**Why the Correct Answer is Right**
Stage II sarcoidosis, as per the Scadding system, is characterized by bilateral hilar lymphadenopathy (BHL) with or without pulmonary infiltrates. This stage represents a moderate form of the disease, with lymph node enlargement and possible lung involvement. The presence of BHL is a hallmark of Stage II sarcoidosis, and it can be accompanied by pulmonary infiltrates, which are areas of abnormal lung density visible on the chest X-ray.

**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because it does not accurately describe the radiographic features of Stage II sarcoidosis. While lymph node enlargement is a key feature, the specific mention of "pleural effusion" is not characteristic of this stage.
**Option B:** is incorrect because it does not accurately describe the radiographic features of Stage II sarcoidosis. While pulmonary infiltrates can be present, the specific mention of "pulmonary fibrosis" is more characteristic of Stage III or IV sarcoidosis.
**Option C:** is incorrect because it does not accurately describe the radiographic features of Stage II sarcoidosis. While lymph node enlargement is a key feature, the specific mention of "normal chest X-ray" is more characteristic of Stage 0 sarcoidosis.

**Clinical Pearl / High-Yield Fact**
When interpreting chest X-rays in patients with suspected sarcoidosis, remember that bilateral hilar lymphadenopathy is a hallmark of Stage II disease, and its presence should prompt further investigation, including imaging and biopsy of involved lymph nodes.

**Correct Answer: C. Normal chest X-ray.**