<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 33-year-old woman comes to the physician for a routine health maintenance examination. She feels well. She was diagnosed with multiple sclerosis one year ago. She has had two exacerbations since then, each lasting about one week and each requiring hospitalization for corticosteroid treatment. Her most recent exacerbation was three weeks ago. In between these episodes she has had no neurologic symptoms. She takes a multivitamin and a calcium supplement daily. Her vital signs are within normal limits. Examination, including neurologic examination, shows no abnormalities. Which of the following is the most appropriate next step in pharmacotherapy?? A: Natalizumab, B: Mitoxantrone, C: Methylprednisolone, D: Interferon beta, E: Supportive therapy only as needed,  <response>: This is a multiple sclerosis treatment question. The patient is a 33-year-old woman with a recent diagnosis of MS who has had 2 exacerbations in the past year requiring hospitalization and corticosteroid treatment. Her most recent exacerbation was 3 weeks ago. In between exacerbations she has no neurologic symptoms. The question is asking for the most appropriate next step in pharmacotherapy. Choice A is natalizumab, a monoclonal antibody used to treat relapsing forms of MS. Choice B is mitoxantrone, an immunosuppressant sometimes used for worsening relapsing-remitting MS. Choice C is methylprednisolone, a corticosteroid used to treat acute MS exacerbations. Choice D is interferon beta, a first-line injectable disease-modifying therapy for relapsing forms of MS. Choice E is supportive therapy only as needed. Based on the patients relapsing-remitting course, the most appropriate next step would be to start a disease-modifying therapy to reduce future relapses and slow disease progression. Natalizumab or interferon beta would be reasonable options. Corticosteroids treat acute exacerbations but do not modify the disease course. Mitoxantrone may be an option for more severe relapsing forms of MS but has potential cardiac toxicity. Supportive therapy alone would not address the underlying disease.D: Interferon beta 