Which of the following is essential in mission planning for reducing risks?

Route selection is essential in mission planning for reducing risks because it directly impacts the safety and efficiency of the mission. By carefully determining the path an operation will take, planners can avoid hazardous areas, hostile territories, and environmental obstacles that could jeopardize the mission’s success. A well-selected route considers factors like terrain, weather, and potential threats, allowing for strategic and tactical advantages during execution.

Crew training, while critical for ensuring that personnel are prepared to handle various situations, does not directly influence the mission’s planned trajectory. Aircraft design is important for overall operational capacity but generally pertains more to the capabilities of the aircraft rather than the specifics of mission planning. Enemy mapping focuses on understanding the adversary's positions and movements, which can help in planning, but it is the choice of the route that ultimately determines how effectively those considerations are integrated into the operation.