Programs enabling conversion of the file:
If your objective is to convert the file from BONK to the file M4A, you can use any of the applications listed. BONK to M4A conversion process in every program intended for this purpose (so-called converters) is very intuitive and everyone is able to manage converting a file.
However, bear in mind that the list may also include programs to support and work with the indicated extensions BONK and M4A - and not only converters. In such a case, you need to open the source file BONK and from the options available in the program, choose ”Save as... M4A" or "Export to M4A".