At this intersection, who should go first?

At this intersection, who should go first?
A)The yellow car, because it is joining the priority road.
B)The orange car, because it has priority over the other vehicles.
C)The truck, because it is approaching from the right.Correct
When there is no sign regulating right of way, the driver is obliged to yield to vehicles approaching from the right. Therefore, the truck goes first, then the orange car, and finally the yellow one.