Some Research on Possible Genetic Factors Involved in Autistic Disorder

Some research on possible genetic factors involved in autistic disorder has compared the parents of children with autistic disorder to parents of children with Down syndrome. In what way are the parents of autistic children different?

A) They are more likely to be aloof and hypersensitive.
B) They have an elevated rate of delusions and hallucinations.
C) They tend to exhibit a number of minor neurological dysfunctions that do meet the diagnostic criteria for a disease.
D) Parents of children with autistic disorder exhibit similar emotions and behavior to those found in parents of children with other serious disorders, although their responses are at a more extreme level.