Most of the research on the effects of heredity on addiction has been devoted to __________

Certain reproductive technologies have made it possible to do which of the following?

A) determine the sexual orientation of fetuses B) allow parents to select the sex of their children C) select the healthiest embryos to carry to birth D) select embryos for optimal height and weight

In an experiment testing the effects of a drug on behavior, whether or not a subject receives a drug represents the:

a. dependent variable b. independent variable c. control variable d. random variable