Which vehicles are allowed to proceed at the controlled intersection?

In a controlled intersection, vehicles are typically regulated by traffic signals or signs, which dictate the movement of vehicles based on priority rules. If option D indicates that vehicles 2 and 3 are allowed to proceed, it suggests that these vehicles have either a green light or a stop sign indicating they can move safely through the intersection.

The reasoning here can be grounded in right-of-way rules, which usually state that vehicles facing a green signal have the right to proceed. Often, vehicles that arrive first have priority as well, provided they can do so legally and safely. If vehicles 2 and 3 are both clear to move based on the traffic controls present, it would mean these vehicles have been granted the right of way.

Contextually, the other choices imply that either only one vehicle is allowed or that certain combinations do not meet the criteria under the traffic controls in place. Understanding the specific signals or signs that govern the intersection can clarify which vehicles should proceed, emphasizing the importance of following traffic regulations for safe driving.