Instead of simply repeating a series of numbers he wants to remember, David mentally associates the numbers with meaningful dates such as his friends' birthdays. This best illustrates

manifest functions are the recognized and intended consequences of any social pattern, while latent functions are those unrecognized and unintended consequences. to analyze the manifest functions of any social institution, we have to study its contribution to the continuation of a group, community, or society.

the answer is d.index

answer; ///he could not explain why the continents drifted;