Alex, a 9-year old boy, is frightened and distressed when he is at school. He feels better when his father comes to pick him up, but in the morning when he has to get ready for school, he becomes highly anxious. By the time he is dropped off at school, he is panicked and sobbing. The most likely diagnosis for Alex is
O Separation anxiety disorder
O Dementia
O Paranoid personality disorder
O Attention defecit hyperactivity disorder