Final answer:
The treatment that shall be permitted for brazing the cut ends of a tube to be installed in a medical gas pipe system involves an argon gas purge, rolling or deburring the cut ends, and possibly adding extensions for brazing.
Step-by-step explanation:
The treatment that shall be permitted for brazing the cut ends of a tube to be installed in a medical gas pipe system is A) a argon gas purge must be done. This is necessary to remove any impurities and create a clean environment for brazing. Additionally, option B (cut in maybe rolled smooth or be deburred) and option C (extensions need to be added for brazing) are also correct, as these steps help ensure a proper joint and improve the brazing process.