a) Just sit there, in the middle of the intersection, blocking traffic.
b) Attempt to back up, hoping there are no other cars behind you in the left turn lane blocking your path.
c) Continue through the intersection.
Unless the law says "never stop in the intersection in the first place", I can't imagine it enforcing any option other than c.
Most states say it's OK if you enter the intersection on yellow, but a handful (not including WA, but including neighboring OR) require that you clear the intersection before the red appears.
I've sometimes wondered if "entering the intersection" includes entering the crosswalk adjacent to the intersection.
https://www.reddit.com/r/todayilearned/comments/57ajjq/til_w...
Wait, why? No new car should enter the intersection when the lights turn to yellow. The yellow light should last long enough for everyone to be able to safely drive off the intersection, in orderly manner.
Cars will obviously enter the intersection under a yellow. It's why we have a yellow.
Even if everyone wanted to stop for every yellow, at 35 mph with average reaction time, cars will travel a minimum of 100 feet after the yellow phase starts. Some of those cars will enter the intersection.
With a typical 4 second yellow, some drivers don't even choose to stop for the first half of the yellow, of course.