Which of these served as the best predictor of long-term retention of mathematics knowledge, in Bahrick's studies on the long-term retention of knowledge?

Comparing the same group of people on the same measure(s) over a lengthy time period defines _______ research

a. longitudinal b. cross-sectional c. basic d. applied

The fact that parent and offspring may differ is irrelevant for natural selection

Indicate whether the statement is true or false