Final answer:
Do not make a U-turn if not visible by all road users, including drivers, pedestrians, and cyclists, to ensure everyone's safety.
Step-by-step explanation:
You should not make a U-turn on a curve or near the top of a hill if you cannot be seen by all of the above: other drivers, pedestrians, and cyclists.
It is important for the safety of everyone on the road. Situations where visibility is poor can lead to accidents, as others may not have enough time to react to your vehicle making a U-turn. Ensuring visibility is critical to avoid putting yourself and others, including pedestrians and cyclists who use the road, at risk.