Which of the Following Best Explains Why Early Cross-Sectional Research

Multiple Choice

Which of the following best explains why early cross-sectional research found that intelligence declines with age?

A) Cross-sectional studies compare groups of people over an extended length of time.
B) Early cross-sectional studies were limited because a large number of participants withdrew from the studies.
C) Cross-sectional studies compare groups of people who are the same age.
D) Early cross-sectional studies compared people of different eras who had varying levels of education and different family experiences.