Which statement describes the relationship between classes and objects?

The relationship between classes and objects is fundamental in object-oriented programming. Classes serve as blueprints for creating objects. When an object is created based on a class, it is referred to as an instance of that class. Therefore, saying that objects are instances of classes accurately reflects this relationship.

When you define a class, you define a specific structure and behavior that can be used to create multiple objects. Each of these objects can hold different values for the attributes defined in the class, but they share the same methods and properties defined by their class. This is why option D correctly represents the relationship: every object is an instance of the class from which it was created, encapsulating the functionality and attributes that the class provides.

Classes can indeed exist without objects being created from them, which is why the statement about classes existing without objects does highlight part of the relationship, but it does not completely capture the essence of how classes and objects interact in programming.