<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 2-year-old boy is brought to the physician by his parents for a well-child visit. During his last well-child visit 9 months ago, the patient had not begun talking. The parents report that their son frequently avoids eye contact and has no friends at daycare. He was born at term and has been healthy except for an episode of otitis media 6 months ago, which was treated with amoxicillin. His immunizations are up-to-date. He is at the 95 percentile for height, 20 percentile for weight, and 95 percentile for head circumference. He appears shy. His temperature is 37C 98.6F, pulse is 120min, and blood pressure is 10055 mm Hg. Examination shows elongated facial features and large ears. The patient does not speak. He does not follow instruction to build a stack of 2 blocks. Throughout the examination, he continually opens and closes his mothers purse and does not maintain eye contact. Which of the following findings is most likely to confirm the diagnosis?? A: An additional X chromosome, B: Mutation on chromosome 15, C: CGG trinucleotide repeats on x-chromosome, D: Defective phenylalanine hydroxlyase activity, E: Three copies of the same chromosome,  <response>: This is a clinical vignette describing a 2-year-old boy with developmental delay, poor social interaction, and stereotyped behaviors. The key findings are lack of speech, poor eye contact, lack of interest in peers, repetitive behaviors, and failure to follow simple instructions. This presentation is most consistent with autism spectrum disorder. The question asks which genetic test would confirm this diagnosis. Autism spectrum disorder is strongly associated with mutations and copy number variations affecting multiple genes, but one of the most consistent findings is mutation or duplication of the MECP2 gene on chromosome Xq28. Therefore, the test most likely to confirm the diagnosis in this patient is testing for CGG trinucleotide repeats on the X chromosome, choice C.C: CGG trinucleotide repeats on x-chromosome 