Investigations of the Causes of ADHD Have Found That Environmental

Investigations of the causes of ADHD have found that environmental toxins,such as food additives and lead

A) do not explain more than a small percentage of cases.
B) are usually the cause of the disorder in those children with an organic basis to their ADHD.
C) are more likely to cause attentional problems without hyperactivity,but not in those children with both attentional problems and hyperactivity.
D) cause subtle attentional problems,but not to the degree of ADHD.