Which of the following is NOT affected by the use of namespaces?

The concept of namespaces in PHP is designed to help avoid name collisions between classes, functions, and constants. When a namespace is defined, it provides a way to encapsulate these entities, allowing you to use the same names in different contexts without conflict.

In the context of the question, variables are indeed not affected by namespaces. Variables in PHP are always in the global scope unless explicitly defined within a function or class method; they do not partake in the scoping behavior that namespaces provide for classes, functions, and constants. As a result, the same variable name can be reused without concern for namespace conflicts, making them effectively exempt from the namespace mechanism.

In contrast, functions, classes, and constants are directly impacted by namespaces since they are subject to the rules of encapsulation. The use of namespaces helps manage these entities efficiently, particularly in larger applications where naming conflicts could be common.