The Most Likely Reason for the Dramatic Increase in the Diagnosis

The most likely reason for the dramatic increase in the diagnosis of autism spectrum disorder is

A) greater awareness of symptoms and broader application of the diagnosis to a wider array of behaviors.
B) chemicals used in the processing and delivery of vaccinations given to children.
C) couples having their first child are older now than in past generations.
D) lead contamination in municipal water supplies in many locales.