**Core Concept**
Heberden nodes are a clinical sign associated with osteoarthritis, particularly affecting the distal interphalangeal joints. They represent a type of bony enlargement or spurring that occurs as a result of degenerative joint disease.

**Why the Correct Answer is Right**
Heberden nodes are formed due to the accumulation of calcium pyrophosphate dihydrate (CPPD) crystals or osteophytes within the joint space, leading to bony overgrowth and eventual formation of a bony prominence. This process is often accompanied by tenderness and limited mobility of the affected joint. The characteristic appearance of Heberden nodes is a hard, bony lump at the distal interphalangeal joint.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because Heberden nodes are not typically associated with rheumatoid arthritis, which affects the proximal interphalangeal joints instead.
**Option B:** Incorrect because Bouchard's nodes are a similar but distinct clinical sign associated with osteoarthritis, specifically affecting the proximal interphalangeal joints.
**Option C:** Incorrect because ganglion cysts are benign tumors that occur in the hand, but they are not related to Heberden nodes or osteoarthritis.

**Clinical Pearl / High-Yield Fact**
Heberden nodes can be a useful clinical clue for diagnosing osteoarthritis, particularly in the hands. They are often associated with a history of repetitive strain or trauma to the affected joint.

**Correct Answer: B. Bouchard's nodes.**