You Are Baffled About How to Untangle the Influence of Heredity

You are baffled about how to untangle the influence of heredity and environment on intelligence. According to the textbook, you should

A) do a longitudinal study where you give people IQ tests every two years from infancy to early adulthood.
B) calculate the IQ of parents and their offspring, which would show the influence of the environment.
C) measure and compare the IQs of identical twins, of fraternal twins, and of siblings reared either together or separately.
D) map the genes responsible for intelligence.