What is the purpose of a constructor in a class?

The purpose of a constructor in a class is fundamentally to create an instance of that class. When a constructor is called, it initializes new objects and can set initial values for properties or execute any setup procedures necessary for the new instance.

In object-oriented programming, a class serves as a blueprint for creating objects. Without a constructor, you wouldn't be able to effectively instantiate or create any objects from your class, as there would be no mechanism to allocate memory for the objects and provide necessary initial values. This instantiation process is critical because it transitions the class definition to an actual usable entity in your code, which can then have its properties accessed and methods invoked.

While defining class properties, supporting inheritance, and establishing visibility are important aspects of class design, they are not the primary role of the constructor itself. The constructor specifically focuses on creating instances, making option B the most accurate choice in this context.