Three of the Following Statements About the Effects of Heredity

Three of the following statements about the effects of heredity and/or environment on intelligence are accurate. Which one is not accurate?

A) Children tend to get higher IQ scores when they attend school regularly.
B) Some toxic substances in children's homes or neighborhoods can adversely affect their cognitive development.
C) Biologists working in the Human Genome Project have recently identified the chromosome that carries the "intelligence" gene.
D) On average, children's performance on intelligence tests has risen around the world, suggesting that improvements in environmental conditions enhance IQ.