Under which condition can a vehicle partially or fully cross into the next lane?

A vehicle can partially or fully cross into the next lane primarily when traveling on multi-lane roadways, which often have designated lanes for different types of traffic and allow for safer lane changes when done in accordance with traffic regulations. This situation provides the opportunity to maneuver into a different lane smoothly, assuming that it is safe to do so, such as when signals are used and there are no obstacles in the adjacent lane.

While light traffic (the second choice) might generally provide more flexibility for lane changes, it does not inherently constitute a valid condition to cross into another lane, as road rules and safety always take precedence, regardless of traffic volume. The option concerned with turning right at an intersection relates to lane usage specifically at that junction, but it does not universally apply to all scenarios where lane changes are concerned. As for nighttime driving, the condition of light, while essential for visibility, does not provide a lawful basis for crossing lanes.

Thus, the condition that best fits the context of when a vehicle is allowed to cross into the next lane is when on multi-lane roadways, emphasizing adherence to traffic laws and driver safety.