It is possible to find in international court decisions some general principles of law, among which are: 

• good faith,
• obligation to make reparation,
• res judiciata (a matter may not, generally, be relitigated once it has been judged on the merits),
• lex specialis derogate legi generali (special law should prevail over general law),
• lex posterior derogate legi priori (more recent law prevails over an inconsistent earlier law),
• fair trial,
• liability for fault, and
• exhaustion of local remedies

As also understood from the information given, the correct answer is A.