Which of the following actions represents proper taxi procedures?

The action that represents proper taxi procedures is to observe traffic and follow ground markings. This is critical in ensuring safety on the ground, as it helps to manage interactions between moving aircraft, ground vehicles, and pedestrians in the airport environment. Adhering to ground markings assists in navigating the taxiways and runways, preventing potential collisions and ensuring that all aircraft are safely positioned for takeoff or arrival. Proper situational awareness through traffic observation is also essential in avoiding any accidents during ground operations.

Other actions, such as accelerating rapidly to takeoff speed, shutting down engines during taxi, or flying below minimum altitude, violate established protocols for safe operations and do not pertain to proper taxiing. These would pose significant safety risks and are not in line with standard aviation practices.