According to Your Textbook, Who Is Most Correct About Influences

According to your textbook, who is most correct about influences on intelligence?

A) John, who believes that anyone can be either extremely bright or very unintelligent given the proper environment
B) Sandy, who thinks intelligence is purely a result of the genes one is given
C) Rachel, who feels intelligence is determined by a combination of heredity and the environment
D) Helen, who believes there is no way to determine the influence of heredity and environment on intelligence