Road rules everywhere, A is always first because it’s going straight eventhough it arrived last. B & C have to wait until the road is clear. Since B has “give way”, B have give the way for any incoming traffic. So C can go second. Lastly, B can go last when the road is really clear.
While the road sign on the road is imo incomplete. There should be a continuous line in front of each. But idk, I don’t have driving license and never drive car.
Aturan prioritas: 1. Polisi lalu lintas 2. Lampu lalu lintas 3. Rambu lalu lintas 4. Kiri duluan kalau di UK, Jepang, India, Indonesia karena jalan lajur kiri