What is the meaning of the following traffic sign?

- Correct answer: Path for bicycles only.
- Bicycle crossing.
- Separate bicycle paths on a freeway.
- Joint path for cyclists and pedestrians.
Why this is the answer
The correct answer in the official bank: Path for bicycles only.
A round blue sign is a mandatory sign, and when it shows only a bicycle, it marks a path meant for bicycles only. Motor vehicles and pedestrians may not use it. A joint path for cyclists and pedestrians is shown by a blue sign with both a bicycle and a pedestrian symbol, so that option does not fit here.