<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:An otherwise healthy 27-year-old man presents to his dermatologist because of a rash over his knees. The rash has been present for 5 weeks and is moderately itchy. Physical examination reveals erythematous plaques covered with silvery scales over the extensor surface of the knees as shown in the image. Which of the following is the best initial step in the management of this patients condition? ? A: Skin biopsy, B: Oral corticosteroids, C: Topical corticosteroids andor topical vitamin D analog, D: Oral methotrexate, E: Oral cyclosporine,  <response>: This is a clinical vignette describing a 27-year-old man with a 5 week history of an itchy rash on his knees. The rash is described as erythematous plaques covered with silvery scales localized to the extensor surfaces of the knees. This presentation is classic for psoriasis. The question asks for the best initial management. Biopsy is unnecessary with this classic presentation. Oral methotrexate and cyclosporine are systemic immunosuppressants that would not be first-line. Topical corticosteroids and vitamin D analogs are the mainstays of topical treatment for mild to moderate psoriasis. Oral corticosteroids may provide temporary improvement but are not recommended for long-term management due to side effects.Therefore, the best initial management would be topical corticosteroids andor vitamin D analogs.C: Topical corticosteroids andor topical vitamin D analog 