The red car goes first, because it has the advantage over the green car. Since the traffic light's green signal is on, the intersection is controlled, and the requirements of the priority signs (2.1, 8.13) are disregarded (clause 173). Both cars are moving on the green signal: the green car is turning left, and the oncoming red car is turning right. Under the Rules, when turning left on a green traffic light signal, a driver must give way to vehicles coming from the oncoming direction going straight or turning right (clause 90).
Option 2. The green car must give way, because when turning left it crosses the path of the oncoming red car.
priority
green
8.13