What happens when air can no longer hold any more water vapor?

When air can no longer hold any more water vapor, this situation leads to condensation. This process occurs when the air reaches its saturation point, meaning it has reached 100% relative humidity. At this point, any additional water vapor cannot remain in the gaseous state and begins to change back to liquid form. This transformation can manifest as dew, fog, or rain, depending on the conditions present.

The reason condensation is the correct answer is that it is the direct result of the air's inability to retain moisture. When temperatures drop or when the air is cooled while holding water vapor, the water vapor molecules start to come closer together and eventually transform into liquid water droplets. This is fundamental to the water cycle and is illustrated in everyday weather phenomena.