To define each of the set classes as a property of the sets object (namespace) for the module, the statement is

sets.SingletonSet = sets.extend(...);

sets = sets.AbstractEnumerableSet.extend();

sets.SingletonSet = sets.AbstractEnumerableSet.extend(...);

To define each of the set classes as a property of the set

1.	To define each of the set classes as a property of the sets object (namespace) for the module, the statement is
A.	sets = sets.AbstractEnumerableSet.extend();
B.	sets.SingletonSet = sets.AbstractEnumerableSet.extend(...);
C.	sets.SingletonSet = sets.extend(...);
D.	sets = sets.extend(...);
Answer» C. sets.SingletonSet = sets.extend(...);