The correct answer is: B. programmer-defined
Container classes are a type of data structure that can be used to store and organize data. They are often used to store collections of objects, such as lists, arrays, and sets. Container classes can be carefully constructed to work with structures that are not programmer-defined. This means that they can be used to store and organize data that is not defined by the programmer.
For example, a container class could be used to store a list of names. The names in the list could be defined by the user, or they could be generated by the program. The container class would not need to be changed in order to store the names, regardless of how they were defined.
Container classes are a powerful tool that can be used to organize and store data in a variety of ways. They are often used in conjunction with other data structures, such as arrays and sets, to create more complex data structures.
Here is a brief explanation of each option:
- A. valid without container classes
This option is incorrect because container classes are not required to store data. Data can be stored in a variety of ways, without the use of container classes.
- B. programmer-defined
This option is correct because container classes can be used to store data that is not defined by the programmer.
- C. type-specific
This option is incorrect because container classes can be used to store data of any type.
- D. public
This option is incorrect because container classes do not need to be public in order to be used.