What is essential for method names in programming languages?

The requirement that method names must be unique within their class is fundamental to programming languages. This uniqueness allows the language interpreter or compiler to identify and differentiate between methods that may share the same name but perform different functions or belong to different classes. If there are multiple methods with the same name, it could lead to ambiguity and confusion when the method is called, as the system wouldn't know which specific method to execute.

This principle is essential for proper functionality and maintainability of code. By ensuring that each method name is unique within its class, developers can avoid unintended behavior and improve the clarity of their code structure. While other options regarding method naming conventions may have merits—such as brevity or not conflicting with built-in functions—ensuring uniqueness within the class is critical for method identification and execution within the program's context.