A 3-Year-Old Boy Is Brought to the Office by His

A 3-year-old boy is brought to the office by his parents due to a concern of his behavioral difficulties.  His mother says, "He is physically healthy but has become more defiant and often resists our instructions during breakfast meal.  He plays roughly with his 5-year-old brother and throws tantrums when he has to share his toys or put them away."  His preschool teacher describes him as an "active child" who sometimes talks out loud to classmates while the teacher is speaking.  He is easily distracted and often gets up to walk around the classroom.  The patient is able to draw circles, speak 3-word sentences, go up stairs with alternating feet, and use the toilet but cannot wipe himself.  His parents express concern about his inability to dress himself and about his bed-wetting that occurs approximately twice a week.  Physical examination is unremarkable.  Which of the following is the most likely explanation for the child's behavior?

A) Attention-deficit hyperactivity disorder
B) Conduct disorder
C) Developmental delay
D) Disruptive mood dysregulation disorder
E) Normal development
F) Oppositional defiant disorder