Which Example Lends the Strongest Support to an Environmental Explanation

Multiple Choice

Which example lends the strongest support to an environmental explanation of intelligence?

A) Bright children take better advantage of their environmental resources.
B) Siblings raised in different homes have IQs of 100 to 120.
C) Children with intellectual disabilities who are moved from institutions into adoptive homes have an average gain of 30 IQ points.
D) Minority groups in the United States have a mean IQ that is 15 points below the mean of the majority.