methodA calls methodB. methodB calls methodC and methodD.
1. methodA runs in TxA.
2. Since methodB's transaction attribute is Required and it is called from methodA with an existing transaction context TxA, methodB runs in that existing transaction of TxA.
3. methodC's transaction attribute is NotSupported and it is called from methodB. Since there is an existing transaction TxA for methodB, the context for the caller method (methodB) will be suspended in this case and methodC will run in an "unspecified transaction context" .
4. methodD's transaction attribute is RequiresNew and it is called from methodB. Since there is an existing transaction TxA for methodB, the caller's (methodB) transaction TxA gets suspended, and methodD will run with a new transaction TxD.
So, the correct answer is : methodA (TxA) --> methodB (TxA) methodB (TxA) --> methodC (no transaction context) methodB (TxA) --> methodD (TxD)