What is unique about the "solo" section that is being heard in this excerpt?

Group of answer choices

This was the first recording done on magnetic tape, and features the same performer "soloing" with her$/$himself

It is freely improvised every time, and this is just one of the millions of possible examples in recordings

The solos would have been performed over the radio by individuals in different cities in different time zones

The solos became standardized both in performance and performing order, and were written down so that they remained the same for nearly every performance