**Core Concept**
Simple bone cysts are typically characterized by their well-defined, lytic lesions with a thin cortical shell, usually found in the metaphysis of long bones. Unlike other bone lesions, simple bone cysts tend to have a more uniform, non-expansile appearance, often without significant cortical disruption or eccentric growth.

**Why the Correct Answer is Right**
Simple bone cysts are known for their central, non-expansile location within the bone, typically not extending beyond the metaphyseal region. This central location is due to the cyst's origin from the bone marrow space, leading to a more symmetrical, non-eccentric appearance on radiographs. Unlike other bone lesions, simple bone cysts do not exhibit significant cortical disruption or eccentric growth, distinguishing them from other options.

**Why Each Wrong Option is Incorrect**
**Option A:** Giant Cell Tumors (GCTs) are typically eccentric in location, often extending into the epiphysis or the articular surface, with a characteristic "soap bubble" appearance due to their lytic, expansile nature.

**Option C:** Osteochondromas are the most common type of benign bone tumor and are often located near the growth plate, with an eccentric appearance due to their origin from the metaphyseal cortex.

**Option D:** Aneurysmal bone cysts are characterized by their expansile, lytic lesions with a thin cortical shell, often exhibiting an eccentric growth pattern due to the accumulation of blood-filled spaces within the bone.

**Clinical Pearl / High-Yield Fact**
When evaluating bone lesions, it's essential to remember that their eccentricity can provide valuable clues about their origin and behavior. Eccentric lesions often indicate a more aggressive or expansile process, while central lesions like simple bone cysts may suggest a more benign or less aggressive etiology.

**✓ Correct Answer: B. Simple bone cyst**