The TBO Implementation class of doc_type_a, which is a sub-type of dm_document, extends
DfDocument and overrides the doSave() method. A new object type, doc_type_b, is inserted in the
hierarchy between dm_document and doc_type_a. Now, doc_type_a is a sub-type of doc_type_b.
What is the outcome of creating an object of type doc_type_a, assuming the an_attribute exists at
the doc_type_b level?

A.
The value of an_attribute is set to doc_type_A.

B.
The value of an_attribute is set to doc_type_B.

C.
A ClassCastException is thrown as the doc_type_a TBO implementation class does not extend
docTypeBTBO class.

D.
The value of an_attribute is blank.