Sorry to interrupt but Nehul is right:
as we know NO BMT for entity bean
but is wrong for :
if you are using CMT in that case entity bean will be abstract
Entity beans have Bean Managed Persistance BMP or Container Manged Persistance CMP. But they only have Container Managed Transactions CMT.
So if Entity bean is BMP it is concrete and if is CMP it is abstract.
I'm agree with Prasad that something smells about the question.