My exam cloud mock 3, about restrictions on bean managed transaction

[Himai Minh]

Which two are restrictions of beans with bean-managed transactions?
A. The NOT_SUPPORTED transaction attribute must be chosen.
B. Clients calling with a transactional context are prohibited and will result in an exception.
C. A stateful session bean must commit a started transaction before a business method returns.
D. A bean that starts a transaction must complete the transaction before it starts a new transaction.
E. A message-driven bean instance must commit a transaction before the onMessage method returns.
Given answer : D and E

But I think the answer should be B and E.
I think B is refering to nested transaction, which is not supported by EJB container.
For D, a bean can suspend a current transaction and start a new transaction. When that new transaction completes, the current
transaction resumes. There is an interface, TransactionManager, which defines suspend() and resume() methods.

[Frits Walraven]

No, D and E are correct.

I think B is refering to nested transaction, which is not supported by EJB container.  

D is referring to nested transactions: "A bean that starts a transaction must complete the transaction before it starts a new transaction." , you cannot do this in a Bean managed bean:

userTransaction.begin();
..
userTransaction.begin();
...
userTransaction.commit();
userTransaction.commit();

Option B is OK because it is allowed for a client to call a BMT bean with a transaction context, however the container will then suspend the active client transaction.