In the years 2030–2040, the number of Americans 85 years old steadily falls from 9.6 million to 1.4 million

Many stepfathers and stepchildren eventually form harmonious, close relationships. How does this happen?

a. The stepfather brings home gifts frequently and establishes weekly allowances. b. The stepfather completely ignores his stepchildren until they are ready to approach him. c. The stepfather acts warmly and openly to his stepchildren and does not immediately try to assert stern authority. d. The stepfathers assert themselves immediately so that the stepchildren know who the disciplinarian is.

Before a researcher can study the effects of a new drug on cancer patients, she first assigns individuals to the control group and the experimental group. Each study participant has an equal chance of being assigned to either group

This procedure is known as A) correlation. B) cross-sectional method. C) longitudinal method. D) random assignment.