<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 7-year-old boy is brought to his pediatrician by his mother who is worried about his clumsiness. She states that over the past 3 months she has noticed progressive weakness. He used to climb trees and run outside with his cousins, but now he says he gets too tired. Shes recently noticed him starting to walk funny, despite having muscular legs. Upon physical examination, the patient has calf muscle hypertrophy. He uses his arms to rise out of the chair. Labs are obtained that show an elevated creatine kinase. Genetic analysis detects a dystropin gene mutation. A muscle biopsy is performed that reveals reduced dystrophin. Which of the following is the most likely diagnosis?? A: Becker muscular dystrophy, B: Duchenne muscular dystrophy, C: Fragile X syndrome, D: Pompe disease, E: Spinal muscular atrophy,  <response>: This is a clinical vignette describing a 7-year-old boy with progressive muscle weakness and abnormal gait over the past 3 months. The history and physical exam findings of calf hypertrophy, use of arms to rise from chair, elevated creatine kinase, and reduced dystrophin on muscle biopsy are consistent with a muscular dystrophy. The dystrophin gene mutation narrows the diagnosis to a dystrophinopathy like Duchenne or Becker muscular dystrophy. Duchenne muscular dystrophy typically presents at a younger age around 3-5 years old and causes more rapid progression of weakness compared to Becker muscular dystrophy. Therefore, the clinical presentation is most consistent with Becker muscular dystrophy. Fragile X syndrome, Pompe disease, and spinal muscular atrophy are incorrect and unrelated to the clinical and diagnostic findings described.A: Becker muscular dystrophy 