A<br/>19-year-old man had repeated left ankle swelling and pain for 1<br/>year.He also said that he had back pain and a sense of low back<br/>stiffness in the past 2 years.These symptoms were severe at night,<br/>aggravated after sitting for a long time, and relieved after<br/>exercise.Laboratory test show HLA-B27 (+).what is his most possible<br/>disease? ____ A: Rheumatoid<br/>arthritis B: Gout C: Ankylosing<br/>spondylitis D: Osteoarthritis E: Infectious<br/>arthritis