With Regard to Childhood Behavioral Problems and Age of Youth

With regard to childhood behavioral problems and age of youth,

A) little relationship exists between age and the occurrence of problems.
B) sometimes what seems to be a relationship between age and the occurrence of a specific disorder may actually reflect the time at which the disorder is first identified.
C) almost all behavior problems of young people appear in some form by age 6.
D) children cannot be diagnosed with a specific disorder until they are at least 8 years old.