The correct answer is: A. one for the declarations and one for the implementations.
A class is a blueprint for creating objects. It defines the properties and methods that objects of that class will have. The declarations of a class are the statements that
define the properties and methods of the class. The implementations of a class are the statements that define how the properties and methods of the class work.It is often helpful to separate the declarations and implementations of a class into two files. This makes it easier to read and understand the code, and it also makes it easier to maintain the code.
Option B is incorrect because void functions are not a special type of function. They are just functions that do not return a value.
Option C is incorrect because public data and private data are not separate files. They are just different types of
data that can be accessed by different parts of the code.Option D is incorrect because primary functions and auxiliary functions are not separate files. They are just different types of functions that can be used in different parts of the code.