In behavior modification, the stimulus that is present when a behavior occurs is referred to as a(n):

Low-birth-weight babies in either developed or developing countries are most likely to be born to parents who have the ____

a. highest socioeconomic status b. fewest resources c. least educational status d. most children

In a national survey of American adults aged 57 to 85 years, what percent of men reported having chronic erectile dysfunction?

a. 99% b. 77% c. 55% d. 33%