A 60 yrs old man with H/O back pain since 3 months.ESR is raised.On examination marked stiffness and mild restriction of chest movements is found.On X-ray ,syndesmophytes are present in vertebrae.Diagnosis is-

• A. Ankylosing hyperosteosis
• B. Lumbar canal stenosis
• C. Ankylosing spondylitis
• D. Degenerative osteoarthritis of spine