Which of the Following Observations Provides the Best Evidence That

Which of the following observations provides the best evidence that intelligence test scores are influenced by heredity?

A) Japanese children have higher average intelligence scores than do American children.
B) Fraternal twins are more similar in their intelligence scores than are ordinary siblings.
C) The intelligence scores of children are positively correlated with the intelligence scores of their parents.
D) Identical twins reared separately are more similar in their intelligence scores than fraternal twins reared together.