The most common example of a metropolitan coordination problem is ________

The United States withdrew from ________________ in 2004 in order to set up a missile defense system in Europe due to the Iranian threat

Fill in the blank(s) with correct word

Tipping takes place when

A) a substantial group of voters switches party allegiance. B) increasing numbers of voters call themselves independents. C) groups of voters grow large enough to change the partisan balance in a district, state, or country. D) birth rates decrease. E) third party candidates enter the race.