<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 9-year-old boy is brought to the physician for a well-child examination. His mother says his teachers report him being easily distracted, lagging behind his classmates in most of the subjects, and frequently falling asleep during class. She says that her son has complained of leg pain on multiple occasions. He is at the 45th percentile for height and 35th percentile for weight. Vital signs are within normal limits. Examination shows ptosis and a high-arched palate. Muscle strength is decreased in the face and hands. Muscle strength of the quadriceps and hamstrings is normal. Sensation is intact. Percussion of the thenar eminence causes the thumb to abduct and then relax slowly. Which of the following is the most likely diagnosis?? A: Spinal muscular atrophy, B: McArdle disease, C: Myotonic dystrophy, D: Juvenile dermatomyositis, E: Duchenne muscular dystrophyn,  <response>: Based on the information provided in the question stem, the key findings are: - 9 year old boy - Easily distracted, lagging behind in school, falling asleep in class - suggests cognitivelearning issues- Complained of leg pain - suggests potential muscleneurological issue- Ptosis and high-arched palate - suggestive of myotonic dystrophy- Decreased muscle strength in face and hands, normal in legs - suggests proximal muscle weakness- Percussion of thenar eminence causes slow relaxation - very suggestive of myotoniaGiven the constellation of cognitive issues, proximal muscle weakness, myotonia, and high-arched palate, the most likely diagnosis is myotonic dystrophy.C: Myotonic dystrophy 