A(n) _________ acts as a factory that creates instance objects.

A class object serves as a blueprint for creating instance objects in object-oriented programming. It defines the structure, behavior, and properties that the created instances will have. When you instantiate a class, you create an instance object, which is a specific implementation of that class. Each instance can have its own unique state, but they all share the properties defined by the class.

In contrast, the other options do not fulfill the role of creating instances. A class attribute is a variable that belongs to the class itself, not to the instances, and is shared among all instances. An instance attribute refers to a variable that is specific to a particular instance of a class. Finally, an instance object is the product of a class, not a factory for creating more instances. Thus, the correct choice highlights the primary function of a class in object-oriented programming—acting as a factory for creating instances.