help with line movement on USC/ASU game

[duma]

line opened at USC -17 . today its at USC -15. Does this movement mean that:

A. Vegas wants you to bet USC since the line is shifting down in favor of USC?

B. Vegas is telling you to take ASU since the line is moving in USC's favor meaning value is being lost each minute that u dont bet on ASU?

i really do not understand line movements at all. i have seen people interpret them any way they want. it doesnt make sense to me. anyone wanna help explain the line movement for this game? thx.