Progressives focused their efforts on solving the problems caused by———- and ———-
a rapid industrial
c. mass immigration
b. urban growth
d. both A and B

Two gymnastics teams are intense rivals. the first team has started recruiting new gymnasts from different cities and even foreign countries in an effort to build a stronger team. after learning this, the second team begins its own recruitment campaign to find even better gymnasts. over a period of months, each team recruits dozens of players, each time trying to find a better recruit than its rival's most recent addition. which idea from the cold war is most similar to this scenario?