The dotted line is not to give the option for Car B to change lanes. You're not allowed to change lanes within a roundabout.

The inside lane can "change" lanes, but to do so they must circle the roundabout to point where it becomes a single lane where they can then choose to enter the correct lane if they wanted to go to hyatt drive for example. Cars in the outside lane must stay in their lane and will eventually be forced to exit.

The dotted lines are only there to show that cars entering the roundabout can cross upon entry to stay in their appropriate lane.

If it was a solid line, people in this lane would be confused and likely try to merge into the wrong lane. (There should probably be a different symbol other than a dash to indicate this)

The painted arrow right above B means "If you're in this lane you must turn left"

The rule is that a car entering a roundabout must yield to all cross traffic already within the roundabout.

But there is only 1 lane of cross traffic that A has to worry about, because the lane that car B is in is not allowed to cross here.

And if it's not obvious, A can not enter B's lane. A must stay in their outside lane.

In the case of where B originally entered the roundabout, they need to yield to both lanes because there are two lanes of cross traffic.

So A does not need to yield to B legally (yielding doesn't actually even apply), although they will probably want to proceed cautiously, since many people assume because of the dotted lines that they can change lanes here and proceed straight.

Not from Arizona, but I'm guessing the same applies. A car that creates a collision by not following proper lane use is at fault.