Question: In a 3GPP file format (3GP), what is the primary purpose of assigning a non-zero `alternate_group` integer to tracks in the Track Header box?
Option 1: To indicate that a track should always be streamed or played simultaneously with another specific track.
Option 2: To identify tracks that contain alternate data for one another, allowing only one to be streamed/play at a time based on attributes like bitrate or language.
Option 3: To signal the beginning of a new streaming session, resetting all previous track associations.
Option 4: To specify the order in which multiple tracks within a group should be played.
Explanation: Assigning a non-zero `alternate_group` integer to tracks signifies that these tracks are part of a group offering alternate versions (e.g., different languages, codecs, or bitrates) of the same content. This allows for the selection and playback/streaming of only one track from the group at any given time, based on attributes such as language preference or available bandwidth, enhancing user experience by providing relevant choices without overwhelming them with simultaneous playback of all alternates.