Bill Bradley, Howard Dean, and Barack Obama funded their campaigns by raising unprecedented amounts of money using

Which of the following is a potential confounding factor in within-subjects designs but NOT in a between-subjects design?

A) regression to the mean B) sequence effects C) attrition D) history

Studies of fertility among the hunting and gathering populations, the French Canadian settlers, and the Irish indicate that __________

a. societies were able to adjust birth rates to adapt to the social and economic environment in which they existed b. these populations had lower life expectancies, because lack of birth-spacing led to poverty and famine c. when population density was low, more land could be devoted to agriculture, and enough food could be grown to eliminate famine d. societies were not able to make adjustments to birth rates or mortality rates