Which Statement About the Predisposing and Etiological Factors Associated with Intellectual

Which statement about the predisposing and etiological factors associated with intellectual disabilities is accurate ?

A) Heredity explains the cause of over one-half of all cases of intellectual disabilities.
B) Down syndrome and fetal alcohol syndrome account for almost 75 percent of all cases of intellectual disabilities.
C) More children develop intellectual disabilities because of infections and brain damage during infancy than because of all other causes put together.
D) In a large majority of cases (80 percent) , the cause of intellectual disabilities is not known.