<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 7-year-old girl is brought to the physician by her mother because she has been increasingly reluctant to speak at school over the past 4 months. Her teachers complain that she does not answer their questions and it is affecting her academic performance. She was born at 35 weeks gestation and pregnancy was complicated by preeclampsia. Previous well-child examinations have been normal. Her older brother was diagnosed with a learning disability 4 years ago. She is at 65th percentile for height and weight. Physical examination shows no abnormalities. She follows commands. She avoids answering questions directly and whispers her answers to her mother instead who then mediates between the doctor and her daughter. Which of the following is the most likely diagnosis?? A: Reactive attachment disorder, B: Autism spectrum disorder, C: Social anxiety disorder, D: Selective mutism, E: Rett syndrome,  <response>: This is a clinical vignette about a 7-year-old girl who has become increasingly reluctant to speak at school over the past 4 months. The key findings are that she avoids answering questions directly at school and whispers her answers to her mother instead. She was born prematurely at 35 weeks and her brother has a learning disability. Otherwise her history and exam are normal. The differential diagnosis includes autism spectrum disorder, social anxiety disorder, selective mutism, and other communication disorders. However, her normal development until 4 months ago makes autism less likely. Social anxiety could cause reluctance to speak, but selective mutism better explains her specific inability to speak at school contrasted with her ability to whisper to her mother. Rett syndrome would not have such an acute presentation.D: Selective mutism 