What action should be taken to adjust levels for multiple audio tracks?

Utilizing the "Audio Automation" controls on the timeline is the most effective method for adjusting levels for multiple audio tracks simultaneously. This feature allows you to manipulate the audio levels directly within the timeline by creating keyframes and adjusting the volume dynamically as the playback progresses. It enables fine-tuning of each track's volume over time without needing to open individual track settings, making it a more efficient option when dealing with multiple audio elements in a project.

This approach not only saves time but also provides a visual representation of how levels change throughout the piece, allowing for easier adjustments and achieving a polished final product. Other methods, while potentially useful, do not offer the same level of efficiency or visual feedback for managing multiple audio tracks in a collaborative manner.