## **Core Concept**
The question tests the understanding of different types of arthritis and their characteristic features, specifically the presence or absence of erosions. Erosions are a hallmark of certain inflammatory arthritides and are detected on radiographs. They indicate a destructive process in the joints.

## **Why the Correct Answer is Right**
The correct answer, **D. Osteoarthritis (OA)**, is characterized by the absence of erosions. OA is a degenerative joint disease primarily involving the cartilage and subchondral bone. It is not typically associated with erosions, unlike some other forms of arthritis. Instead, OA is characterized by joint space narrowing, osteophytes, and subchondral sclerosis on radiographs.

## **Why Each Wrong Option is Incorrect**
- **Option A: Rheumatoid Arthritis (RA)** is incorrect because RA is a classic example of an erosive arthritis. It leads to symmetric joint involvement and erosions, which are a diagnostic criterion.
- **Option B: Psoriatic Arthritis (PsA)** is incorrect because PsA can cause erosions. It is a form of seronegative spondyloarthritis that can lead to significant joint damage, including erosions and new bone formation.
- **Option C: Gout** is incorrect because Gout, or gouty arthritis, can also lead to erosions. The erosions in gout are typically punched-out lesions and can be associated with tophi formation.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the presence of erosions on radiographs helps differentiate inflammatory arthritides (like RA, PsA, and gout) from non-inflammatory or degenerative conditions like osteoarthritis.

## **Correct Answer: D. Osteoarthritis.**