GEB FL 390 is not available due traffic alternative is FL350 advise what does this ATC instruction mean?

A、GEBFL390can’tbeprovidedduetrafficyoucanchooseFL350insteadpleasetellmeyourintension
B、GEBFL390can’tbeacceptedflytothealternateFL350advise
C、GEBFL390isnotavailableduetraffic,descenttoFL350viaalternativelevel
D、GEByoucanflyFL390duetraffic,tellmewhenyouflytoFL350viaalternativelevel