**Core Concept**
The patient's symptoms and laboratory results are suggestive of osteoarthritis (OA), a degenerative joint disease characterized by progressive wear and tear of articular cartilage, leading to bone-on-bone contact and associated pain, stiffness, and limited mobility.

**Why the Correct Answer is Right**
The patient's symptoms of aching pain, worse with exercise and relieved with rest, along with joint tenderness, swelling, and crepitus, are classic features of OA. The absence of rheumatoid factor, antinuclear antibodies, and normal ESR further support OA over other inflammatory arthropathies. OA is typically associated with degenerative changes in the affected joints, which can be visualized on X-rays.

**Why Each Wrong Option is Incorrect**
**Option A:** Joint space narrowing is a hallmark of OA, as cartilage loss leads to a decrease in joint space. This is a likely finding in OA.

**Option C:** Osteophytes are bone spurs that form in response to joint degeneration, often seen in OA. They can cause pain and stiffness, and are a common finding in OA on X-rays.

**Option D:** Subchondral sclerosis is a feature of OA, where the subchondral bone becomes denser and more sclerotic due to increased bone turnover. This can be seen on X-rays.

**Clinical Pearl / High-Yield Fact**
OA is the most common type of arthritis, affecting over 30 million adults in the US, and is often associated with age-related wear and tear, obesity, and genetic predisposition.

**Correct Answer:**
**Correct Answer:** B.