Answer:
A. could only be allowed if Congress authorized it.
Step-by-step explanation:
The decision by the Supreme Court was taken on June 29th 2006, the case was simple the deteinees at Guantanamo bay couldn´t be trialed by a military comission just because, they needed could do it only if they had authorization from congress, which to that time they didn´t have, so the supreme court ruled the trials unconstitutional untill the congress gave authorization.