What attribute must be added to the <audio> element to incorporate default audio operations like play and pause?

The attribute that needs to be added to the <audio> element to incorporate default audio operations like play and pause is controls="controls". This attribute enables the default browser controls for audio playback, which include buttons that allow the user to play, pause, and control the volume of the audio file. Without this attribute, the audio will play without any user interface elements for controlling playback, making it less user-friendly.

Adding controls allows users to interact with the audio element seamlessly, improving accessibility and usability for all users. This is particularly important for web development, as providing user-friendly interfaces is a crucial aspect of creating an effective web application.

The other attributes mentioned serve different purposes: autoplay automatically starts playback when the audio element is loaded, loop replays the audio once it reaches the end, and muted starts the audio playback with the sound off. None of these attributes provide the control interface needed for basic audio operations.