**Core Concept**
Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the spine and sacroiliac joints, leading to fusion of vertebrae and eventual loss of spinal mobility. It is a type of seronegative spondyloarthritis, characterized by inflammation of the axial skeleton and entheses.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of ankylosing spondylitis. AS is associated with the presence of HLA-B27 antigen and is characterized by inflammation of the spinal joints and entheses, leading to new bone formation and eventual fusion of the vertebrae. This process is mediated by various inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1β).

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ankylosing spondylitis is indeed associated with HLA-B27 antigen, which is a strong genetic risk factor for the disease.
**Option B:** This option is incorrect because the disease process in AS involves inflammation of the spinal joints and entheses, leading to new bone formation and eventual fusion of the vertebrae.
**Option C:** This option is incorrect because AS is a chronic inflammatory disease that primarily affects the spine and sacroiliac joints, leading to fusion of vertebrae and eventual loss of spinal mobility.

**Clinical Pearl / High-Yield Fact**
AS is a classic example of a seronegative spondyloarthritis, characterized by inflammation of the axial skeleton and entheses. The presence of HLA-B27 antigen is a strong risk factor for the disease, and patients with AS are at increased risk of developing other spondyloarthritis-related conditions, such as psoriatic arthritis and reactive arthritis.

**Correct Answer:** B.