Which conduct is right?

Your answer is fully correct.

In this situation, the green car must wait because you have priority to turn right after yielding as indicated by the yield signs. The yield signs require the green car to give way to you.

You may turn by observing the traffic signs, which means you do not have to wait for the traffic light to show green if it is red, since the additional yield signs allow you to proceed when it is safe. This rule applies in Germany when yield signs are present and the traffic lights are not green for you.

The third option is incorrect because you are not required to wait for the green light due to the yield signs giving you right of way once it's safe to turn.

This rule helps you understand when you can rely on traffic signs over traffic lights in intersection situations with conflicting signals.