What is the right course of action?

Your answer is correct because you must wait in this situation.

The rule here is about traffic signs and priority. The motorbike is coming from the right but there are "no entry" signs where the motorbike is located. This means the motorbike cannot legally enter this street from its side and does not have the right of way in this situation.

Additionally, you are going straight, and the red car on the right is parked, so it is not moving or interfering. The motorbike should not be on this road at all, so you have the right of way, but because the motorbike might be moving despite the signs, you must wait cautiously to avoid a collision.

In summary, the correct action is for you to wait and ensure the road is clear, while the motorbike is actually not allowed to proceed here. This is why "I have to wait" is the correct choice—patience is necessary when other road users might be violating signs.