Jack wants to test whether runners on his cross-country team improve with his new training regimen. He measures their run times at the beginning of the season and again at the end of the season. Runners in Jack's study improving their times due to running generally and not necessarily due to the new regimen is an example of which of the following threats?a. Selection
b. Maturation
c. History
d. Instrumentation

well it depends i think people around the world are coming around to gay marriage. but if you are talking abortion then wow, so much to talk about. such as men thinking they have the right to choose if women can, the fact there are health concerns if the women can't get one, and many more arguments to discuss. so i would definitely say abortion would be a much more interesting topic.

answer; answer; marginal cost;

answer; expert witness;