What is required for Cs to be eligible for CV bonus in uneven bars?

To be eligible for a CV (Connection Value) bonus on the uneven bars, a skill must demonstrate specific criteria. The correct choice states that the skill must involve a flight or turn. This requirement is crucial because it ensures that gymnasts are incorporating dynamic and challenging elements into their routines, which are necessary for achieving higher scores.

When a skill includes a flight element, it showcases the athlete's ability to leave the bars, which adds difficulty and artistic value. Similarly, incorporating a turn invites additional complexity as the gymnast must manage their body position and control during the rotation. These elements directly contribute to the overall score by elevating the performance's intricacy and showcasing the gymnast's skills.

The other criteria—such as twists, the inclusion of a release after a D element, or being part of a series of connections—are relevant for different aspects of scoring but do not specifically align with the eligibility for CV bonus in the way that including a flight or turn does. Therefore, it becomes clear why this particular aspect is emphasized in determining connection value on the uneven bars.