But
"since mB() executes within mA()'s transaction context, the container will mark it for rollback and throw javax.ejb.EJBTransactionRolledbackException to mA() when mB() encounters a system exception."
So mA() gets the EJBTransactionRolledbackException which is not handled. How come does it translate to EJBException?
Although the answer is correct the explanation is not fully, or I missed smth
