It is easier to explain why the other answers are not correct...
a) ejbPassivate() is not likely to come into play in this scenario and hence is not a usual suspect.
c) ejbCreate() is only involved when the entity is created. Since the question clearly states the the entity was changed, therefore it was already created, then ejbCreate() is not be called.
e) Frankly, this answer does not make any sense.
I remember this question from the IBM ICE
test and we are told the question has exactly two answers, which only leaves b and d.
I think d is poorly worded. It should say something to the extent of the database not supporting transactions or XA protocol, I don't think it should explicitly mention JTA.