Which of the Following Possibly Accounts for the Performance Improvement

Multiple Choice

Which of the following possibly accounts for the performance improvement in IQ tests from one generation to the next?

A) Evolution that occurs slowly.
B) Galton's prediction that higher birthrates observed among those with lower IQ scores would move IQ scores lower.
C) Combined effects of improved education,better health and nutrition,experience with testing,and exposure to a broader range of information
D) All of the above