Which of the following statements is true about the prevalence of attention-deficit/hyperactivity disorder (ADHD) ?

A) Epidemiological studies indicate that 20 percent of children develop ADHD.
B) Boys are more likely than girls to develop ADHD in childhood and early adolescence.
C) Girls with ADHD tend to have more disruptive behavior than boys with ADHD.
D) The percentage of children diagnosed with ADHD is much greater in the United States than in other countries.

Boys are more likely than girls to develop ADHD in childhood and early adolescence. This has been found in numerous studies and is widely accepted in the medical community. While the exact percentage of children with ADHD varies in different studies and populations, it is generally estimated to be around 5-10% of children. There is also some evidence that rates of diagnosis and treatment vary across countries, with higher rates in the US and some other Western countries. However, it is important to note that cultural and societal factors may play a role in these differences, and it is not clear that all cases of ADHD are being accurately diagnosed and treated.