Which of the following correctly describes the meaning of namespace’ feature in C++?

• A. a. Namespaces refer to the memory space allocated for names used in a program
• B. b. Namespaces refer to space between the names in a program
• C. c. Namespaces refer to packing structure of classes in a program.
• D. d. Namespaces provide facilities for organizing the names in aprogram to avoid name clashes.