<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 12-year-old boy presents with progressive clumsiness and difficulty walking. He walks like a drunken-man and has experienced frequent falls. He was born at term and has gone through normal developmental milestones. His vaccination profile is up to date. He denies fever, chills, nausea, vomiting, chest pain, and shortness of breath. He has no history of alcohol use or illicit drug use. His elder brother experienced the same symptoms. The physical examination reveals normal higher mental functions. His extraocular movements are normal. His speech is mildly dysarthric. His muscle tone and strength in all 4 limbs are normal. His ankle reflexes are absent bilaterally with positive Babinskis signs. Both vibration and proprioception are absent bilaterally. When he is asked to stand with his eyes closed and with both feet close together, he sways from side to side, unable to stand still. X-ray results show mild scoliosis. Electrocardiogram results show widespread T-wave inversions. His fasting blood glucose level is 143 mgdL. What is the most likely diagnosis?? A: Ataxia-telangiectasia, B: Charcot-Marie-Tooth disease, C: Duchene muscular dystrophy, D: Friedreichs ataxia, E: Myotonic dystrophy,  <response>: Based on the information provided in the question stem, the key findings are:- 12-year-old boy with progressive clumsiness and difficulty walking - Walks with a drunken-man gait and has frequent falls- Normal developmental milestones- No fever, chills, nausea, vomiting, chest pain, shortness of breath - No alcohol or drug use- Brother had similar symptoms- Normal higher mental functions and extraocular movements- Mildly dysarthric speech- Normal muscle tone and strength- Absent ankle reflexes with positive Babinski sign- Absent vibration and proprioception sense- Unable to stand still with eyes closed - Mild scoliosis on X-ray- Widespread T-wave inversions on ECG- Fasting blood glucose 143 mgdLThe progressive ataxia, dysarthria, absent reflexes, and positive Babinski sign point towards a diagnosis of cerebellar ataxia. The scoliosis and ECG changes suggest Friedreichs ataxia. The family history of similar symptoms in his brother also supports an inherited disorder like Friedreichs ataxia.D: Friedreichs ataxia 