What option must be checked to make a sound play repeatedly?

To play a sound repeatedly in Unity, the option that must be checked is Looping. When this setting is enabled on an Audio Source component, the audio clip will restart automatically once it finishes playing. This allows for continuous playback without needing additional code to manage the restart of the sound.

The other options relate to different functionalities. For instance, "Play on Awake" ensures that the sound plays as soon as the game object becomes active, but it does not affect how many times the sound plays after that. "Play Every Frame" is not a standard setting in Unity and would not apply to sound playback. Randomizing is typically used to alter the playback of sound clips by selecting different clips at random, which does not contribute to repetitive playback of a single sound.