In the penultimate week of the regular season, the Pac-12 decided which teams will play in its championship game for a berth in the 100th Rose Bowl.  Before the season began, Stanford and Arizona State headed many lists for the champions of the North and South Divisions, respectively.  Yet few would have predicted this matchup a week ago, when Oregon gained control of the North and UCLA stood one home victory away from seizing control of the South.  As it turns out, each of the first three Pac-12 championship games will feature a different pair of opponents, and three different teams likely will host them.  No conference has greater parity near the top, a distinction in which the Pac-12 can take pride during this period when it lacks a national title contender.