Final answer:
The concept that allows subclasses to share the characteristics of their superclasses in object-oriented programming is called option 4) inheritance. It is fundamental for code reuse and hierarchical classification of classes.
Step-by-step explanation:
A concept that allows subclasses to share the characteristics of their superclasses is called inheritance (option 4)). This fundamental concept of object-oriented programming (OOP) enables a class to inherit attributes and behaviors (methods) from another class, referred to as its superclass or parent class. Inheritance promotes the reuse of existing code and leads to a hierarchical classification of classes, which simplifies the creation of complex systems.
There are other related concepts in OOP such as aggregation and composition, which are types of association that describe relationships between objects, and multiplicity, which specifies the cardinality of such relationships. However, these concepts do not describe the sharing of characteristics like inheritance does.