Which of the following is a method for aircraft and surface fires integration?

Altitude separation is an effective method for integrating aircraft and surface fires because it helps manage and minimize the risk of friendly fire incidents while allowing for coordinated operations. This technique involves positioning aircraft and ground units at different altitudes to create a safe vertical distance between their operations. By doing this, each can effectively engage targets without complicating their fire paths or operational zones, ensuring a higher degree of safety and effectiveness in combat operations.

Focusing on altitude separation allows command elements to utilize the full capabilities of both air and ground assets, optimizing support and ensuring that each can operate in a manner that minimizes interference. This integration is critical in modern warfare where multiple units must work concurrently in the same operational space.

Other methods, though they have their respective uses, do not address the vertical aspect of operational coordination as directly as altitude separation.