<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 6-year-old girl is brought to the clinic by her mother with fever, sore throat, and a rash. The patients mother says that her symptoms started 3 days ago with a high-grade fever, sore throat, vomiting, and malaise. Twenty-four hours later, she says a rash appeared on the patients neck and, over the next 24 hours, spread to the trunk and extremities. The patients mother mentions she had a bad sore throat about a week ago but denies any chills, seizures, or sick contacts. The patient has no significant past medical history and takes no current medications. Her birth was uncomplicated, and she has been meeting all developmental milestones. The patients vital signs include: pulse 90min, respiratory rate 20min, temperature 39.0C 102.2F, and blood pressure 9050 mm Hg. On physical examination, the patient has a whole-body, erythematous punctate, maculopapular rash, as shown in the exhibit see image. Oropharyngeal examination shows circumoral pallor and a red tongue. The remainder of the examination is unremarkable. Which of the following is the next best step in the management of this patient?? A: Rapid antigen test, B: PCR, C: Serum CRP and ESR, D: Supportive treatment, E: Serology for IgM and IgG antibodies,  <response>: Based on the description, this is likely a case of scarlet fever given the high fever, sore throat, rash, and history of recent strep throat in the mother. The next best step would be to confirm the diagnosis by testing for group A streptococcus. A rapid antigen detection test from a throat swab would provide quick results and be useful to guide antibiotic treatment. PCR would also detect streptococcus from a throat swab but takes longer. CRP, ESR, and serology are not useful next steps. Supportive treatment alone without confirming the diagnosis would be premature.A: Rapid antigen test 