The Most Likely Reason for the Increase in the Number

The most likely reason for the increase in the number of children diagnosed with autism spectrum disorders is that

A) in the 1990s, autism was removed from the U.S. list of disabilities eligible for special education services.
B) the rise has corresponded with the significant increase in the number of infants born with HIV.
C) in the 1990s, Asperger syndrome was removed from the DSM-IV.
D) there is now a broader definition for what used to be just autism.