Three cars approach the intersection, a green car from the west, a dark blue car from the south, and a lighter blue car from the north (in that order); the darker blue car is turning left:
a-the green car should wave on the dark blue car because it is on the right and the lighter blue car is going straight so it should go ahead and go through the intersection so the dark blue car can turn left, and then the green car may proceed
b-the darker blue car should go first because it is to the right of the other cars in the intersection, then the green car, then the lighter blue car
c-the green car should go first because it arrived first, the dark blue car second and the lighter blue car third
I like c, green should be first because green means go, if there is a red car it should go last.