On this ascent, a U-turn is prohibited only when visibility in either direction is less than 100 meters.
The Rules prohibit a U-turn (clause 50) when the road is visible for less than 100 meters in either direction, which means it is allowed with visibility of 100 meters or more. Therefore, a U-turn on this ascent is allowed only if clear visibility of at least 100 meters is ensured from both sides. This makes sure that approaching drivers have enough time to notice your maneuvering vehicle and stop safely.
Option 1. Being able to make the U-turn in one go does not free you from the mandatory visibility requirement.
Option 3. A U-turn on ascents is not automatically prohibited: it is prohibited only when visibility is less than 100 meters.