Which is a recommended water-skiing safety practice?

Holding up a ski after falling is a recommended safety practice in water-skiing because it signals to the boat operator that the skier is in the water and needs assistance. This action increases visibility and ensures the safety of both the skier and the boat crew. When a skier falls, it is crucial to avoid being in the path of the boat as it circles back to pick them up, and holding up a ski helps to communicate their location as well as their need for help.

Other practices, such as wearing a life jacket, are essential for safety but were not presented as the correct choice in this question. Controlling the conditions of water-skiing is significant, so participating in rough weather is unsafe due to increased risks. Lastly, the importance of having a spotter is highlighted since the spotter can assist in monitoring the skier's safety and communicating with the driver about their position in the water.