Mark,
You are correct. The question is ambiguous. Question must clarify about transaction context of Bean method as either of following:
1] Bean method runs in context of the caller�s transaction
2] Bean method runs in context of a transaction that the Container started immediately before dispatching the business method.
3] Bean method runs with an unspecified transaction context.
The exception thrown by Container would differ based on the above mentioned. Client would receive javax.transaction.TransactionRolledBackException, if business method has transaction attribute as either Required, Mandatory, and Supports in this case.
So what transaction attribute is specified for business method on a bean must have been specified in question.
Rest assured. Actual Certification
test would not have such ambiguous questions as per my past experience.

Regards,<br />Sandesh<br />(SCJCP, SCWCD, SCBCD - 99%, OCP-1)<br /> <br />Either find a way or create one.