The correct answer is: A. Code that defines a group of related classes.
A namespace is a way to group related identifiers together. This can be useful for avoiding name clashes, as well as for organizing code. Namespaces are declared using the namespace keyword, followed by a name for the namespace. For example:
namespace MyNamespace
{
class MyClass
{
}
}
The MyClass class is now part of the MyNamespace namespace. To access it from outside of the namespace, you need to use the namespace qualifier:
MyNamespace::MyClass myObject;
You can also use namespaces to group related types together. For example, you might have a namespace for all of your user-defined types, and another namespace for all of your system types. This can help to keep your code organized and easy to read.
Here is a brief explanation of each option:
- Code that defines a group of related classes. This is the correct answer. A namespace is a way to group related identifiers together, which can be useful for avoiding name clashes, as well as for organizing code.
- Code to define hierarchy. This is not correct. A namespace does not define a hierarchy.
- Contains object definition. This is not correct. A namespace does not contain object definitions.
- Contains class definition. This is not correct. A namespace does not contain class definitions.