How must you behave?

Your answer is correct.

When you see an obstacle like a ball on the road, you must slow down immediately to a walking pace to be able to stop safely if a child suddenly appears. Remaining ready to brake means you have to be prepared to stop quickly if necessary. This caution helps avoid accidents, especially since children might be nearby. Driving past at the same speed is dangerous as you may not have enough time to react to unexpected hazards.

In summary, slow down early and stay alert to brake quickly if needed, ensuring safety for all road users.