Which factor contributes to the formation of precipitation during a warm front?

The correct factor contributing to the formation of precipitation during a warm front is condensation leading to cloud formation.

During the approach of a warm front, warm air is forced to rise over the cooler air ahead of the front. As the warm air rises, it cools and can no longer hold all of its moisture. This cooling process leads to condensation, resulting in the formation of clouds. The clouds produced are typically stratiform, which can lead to widespread and steady precipitation. The condensation process is essential in the lifecycle of clouds and precipitation because it transforms water vapor into liquid droplets, ultimately contributing to rainfall as these droplets coalesce and fall.

The other factors mentioned do not correctly depict the mechanism active during a warm front. For example, while rising cool air might occur in specific weather patterns, it doesn't play the primary role in warm front dynamics like the process of condensation does. Similarly, descending stable air typically corresponds with high pressure and clear weather, not precipitation. Lastly, the concept of warm air sinking rapidly contradicts the principles of a warm front, where warm air is actually ascending over the cooler air, not descending.