When Five-Year-Old Aliens Began Elementary School the Teachers Noticed That

When five-year-old Aliens began elementary school the teachers noticed that compared to other children his interests and activities were restricted and he did not interact with other children. His motor behavior was often stereotyped and repetitive, and he appeared clumsy when he walked. A battery of psychological tests reveals no evidence of mental retardation. Based on his age and symptoms, which disorder would mental health professionals suspect in this case?

A) Radios disorder
B) autistic disorder
C) Asperger's disorder
D) childhood disintegrative disorder