<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 28-year-old man presents with one week of redness and discharge in his eyes, pain and swelling in his left second and third toes, and rash on the soles of his feet. He is sexually active with multiple partners and uses condoms occasionally. He denies any recent travel or illness and does not take any medications. Review of systems is otherwise unremarkable. On physical exam, he has bilateral conjunctivitis, dactylitis of the left second and third toes, and crusty yellow-brown vesicles on his plantar feet. Complete blood count and chemistries are within normal limits. Erythrocyte sedimentation rate ESR is 40 mmh. Toe radiographs demonstrate soft tissue swelling but no fractures. Which diagnostic test should be performed next?? A: Rheumatoid factor, B: Anti-cyclic citrullinated peptide antibody assay, C: Antinuclear antibody assay, D: HLA-B27, E: Nucleic acid amplification testing for Chlamydia trachomatis,  <response>: This is a clinical vignette describing a 28-year-old sexually active man presenting with conjunctivitis, dactylitis of the toes, and vesicular rash on the feet. The key findings are conjunctivitis, dactylitis, and vesicular rash, along with elevated ESR. The differential diagnosis includes reactive arthritis, rheumatoid arthritis, psoriatic arthritis, and sexually transmitted infections like chlamydia. Rheumatoid factor and anti-CCP are tests for rheumatoid arthritis. ANA is nonspecific and can be positive in many autoimmune conditions. HLA-B27 is associated with spondyloarthropathies like reactive arthritis. Nucleic acid amplification testing for chlamydia would be the best next test to confirm sexually transmitted infection as the cause of this likely reactive arthritis presentation.E: Nucleic acid amplification testing for Chlamydia trachomatis 