What does a "live" rear axle mean in most ATVs?

A "live" rear axle in most ATVs refers to a configuration where both rear wheels are driven, meaning that they turn at the same rate at all times. This setup provides consistent power to both wheels, which can be advantageous for maintaining traction, especially in challenging terrain or during maneuvers that require stability, such as climbing or cornering.

In contrast, the other options present different axle functionalities that do not align with the definition of a "live" rear axle. For instance, if only one wheel turns, it would characterize a different type of axle that may not provide the same level of traction and could lead to difficulties in off-road conditions. An axle that allows the rear wheels to spin at different rates pertains to a differential setup, which helps navigate turns but is not reflective of a "live" axle. Lastly, an axle that can disengage from the wheels suggests a completely different mechanism typically associated with varying drive systems, which further deviates from the concept of a "live" axle that maintains constant engagement with both wheels.