Although Attention-Deficit/hyperactivity Disorder (ADHD) Is Commonly Diagnosed,the Cause of ADHD

Although attention-deficit/hyperactivity disorder (ADHD) is commonly diagnosed,the cause of ADHD has been difficult to determine.The main reason for this is that

A) ADHD lacks a genetic component.
B) the brains of people with ADHD develop much faster than those without.
C) children with ADHD also typically have other disorders.
D) since behavioral profiles vary,it is likely that there is more than one cause.