**Core Concept**
Bilateral hilar lymphadenopathy (BHL) and reticular densities in the lung fields are characteristic findings in sarcoidosis, a systemic granulomatous disease of unknown etiology. The disease is characterized by the formation of non-caseating granulomas in various organs, including the lungs.

**Why the Correct Answer is Right**
The correct answer is granulomatous inflammation. This type of inflammation is defined by the presence of granulomas, which are aggregates of macrophages and other immune cells that attempt to isolate and eliminate foreign substances or infectious agents. In sarcoidosis, granulomas form in response to an unknown antigen, leading to the characteristic BHL and reticular densities seen on chest radiographs.

**Why Each Wrong Option is Incorrect**
**Option A:** Eosinophilic pneumonia is a type of interstitial lung disease characterized by an infiltration of eosinophils into the lung tissue, but it does not typically present with BHL and reticular densities.

**Option B:** Lymphoma can cause lymphadenopathy, but it is usually unilateral and not associated with reticular densities in the lung fields.

**Option C:** Tuberculosis can cause lymphadenopathy and reticular densities, but it typically presents with cavitation and upper lobe involvement, rather than BHL and bilateral reticular densities.

**Clinical Pearl / High-Yield Fact**
Sarcoidosis can affect any organ system, but the lungs are the most commonly affected. The disease can also cause a wide range of systemic symptoms, including fever, fatigue, and weight loss.

**Correct Answer:** C.