**Core Concept**
Eleidin is a crystalline pigment found in the keratinized epithelium of the skin and certain oral tissues. Its granules are specifically associated with the **stratum lucidum**, a thin, translucent layer that occurs only in thick skin and the oral mucosa, where it is part of the keratinization process.

**Why the Correct Answer is Right**
The **stratum lucidum** is a specialized, non-keratinizing layer of flattened, densely packed cells that form a protective barrier in thick skin and the oral epithelium. It is the **only layer** in the epidermis where **eleidin granules** are present. These granules are derived from keratin and are visible under polarized light microscopy. In dental contexts, eleidin is found in the **hard dental tissues** like enamel, but the granules are specifically localized in the **stratum lucidum** of oral mucosa, not in the deeper layers.

**Why Each Wrong Option is Incorrect**
Option A: The **stratum corneum** is the outermost layer composed of dead, keratinized cells and does not contain eleidin granules.
Option C: The **stratum spinosum** contains keratinocytes and desmosomes but lacks eleidin granules.
Option D: The **stratum basale** is the basal layer where cell division occurs and is not associated with eleidin deposition.

**Clinical Pearl / High-Yield Fact**
Eleidin granules are a hallmark of **keratinized epithelium** and are most clearly seen in the **stratum lucidum** of the oral mucosa and thick skin. Their presence indicates a well-developed, protective epithelial barrier — a key concept in oral pathology and histology.

✓ Correct Answer: B. Stratum lucidum