**Core Concept**
Telescope fingers, also known as "arthritis mutilans," is a rare but severe complication of psoriatic arthritis characterized by the progressive destruction of the joints, leading to a telescoping appearance of the fingers.

**Why the Correct Answer is Right**
In psoriatic arthritis, the joint damage is caused by an abnormal inflammatory response, which results in the erosion of the bone and cartilage. This leads to the characteristic telescoping appearance of the fingers, where the bones appear to be compressed and overlapping. The precise mechanism involves the activation of various inflammatory cells and the release of pro-inflammatory cytokines, such as TNF-alpha and IL-1 beta, which contribute to the joint destruction.

**Why Each Wrong Option is Incorrect**
**Option A:** Rheumatic arthritis is not typically associated with the severe joint destruction seen in telescope fingers.
**Option B:** Rheumatoid arthritis can cause joint damage, but it does not typically result in the characteristic telescoping appearance of telescope fingers.
**Option D:** Reiter's arthritis (also known as reactive arthritis) is a type of spondyloarthritis that can cause joint pain and inflammation, but it is not typically associated with the severe joint destruction seen in telescope fingers.

**Clinical Pearl / High-Yield Fact**
Telescope fingers are a classic sign of psoriatic arthritis, and their presence should prompt a thorough evaluation for other manifestations of the disease, including psoriasis, enthesitis, and dactylitis.

**✓ Correct Answer: C. Psoriatic arthritis**