Laura and Mikail recently learned that their two-year-old son has autism spectrum disorder. However, due to long waits for follow-up support services, Laura and Mikail do their own research online and chat with neighbours about how best to help their young son. After reading several articles, they come to believe that they can cure their son with vitamins and diet. What would you tell Laura and Mikail?

a) Based on available evidence, vitamins and diet do not appear to be an effective treatment for autism.
b) Vitamins and diet may improve their son's symptoms, but it is necessary to consult a professional to determine exactly which dietary deficiencies may be involved.
c) Vitamins and diet are currently being investigated as a promising treatment for autism, but the results are too preliminary to draw any conclusions.
d) Vitamins and diet have been shown to be effective, but the gains are not sufficient to be considered a cure.