What technique is employed when routes to vehicle positions are clear, and units are not under enemy observation or fire?

The correct answer is the Tailgate Technique. This technique is utilized in military operations and security scenarios when the environment is safe enough—specifically, when routes to vehicle positions are unobscured and units are not under direct observation or fire from enemy forces.

The Tailgate Technique allows for a more efficient and rapid movement of personnel and equipment. It is characterized by vehicles positioning closely to one another, enabling a swift escape or maneuver while maximizing the use of available cover and minimizing individual unit exposure. The close arrangement assists in maintaining unit cohesion and rapid response in case of threats, making it particularly effective in scenarios where immediate movement is needed without the constraints of enemy contact.

Other options might describe different methodologies for navigating or positioning units, but the unique circumstances of clear routes and lack of enemy monitoring distinctly categorize the Tailgate Technique as the appropriate choice in this context.