Which statement is true about the visibility of Constructor methods?

The statement that constructors can be private to restrict access is true, as it allows for encapsulation in object-oriented programming. By declaring a constructor as private, you can prevent external instantiation of the class from outside its own code. This is particularly useful in design patterns such as the Singleton pattern, where you want to ensure only a single instance of a class is created and managed within that class itself.

Additionally, making a constructor private can protect the class from being instantiated inappropriately, promoting better control over how and when the class's objects are created. This is a common practice when implementing factory methods or when a class is only meant to provide static utility methods.

On the other hand, public visibility as a default constructor option would mean that classes can be instantiated freely from outside, contradicting the encapsulation principle. Saying that constructor visibility can only be internal is incorrect because it overlooks the flexibility of visibility options provided in object-oriented designs. Lastly, claiming that all constructors must be public suggests a misunderstanding of the principles of access control and encapsulation in programming.