What differentiates a variable from a constant in programming?

The distinction between a variable and a constant in programming is primarily centered on mutability—whether the value can be altered during program execution. A variable is a named storage location that can hold different values throughout its lifecycle, allowing for updates and modifications as the program runs. This is essential for operations where data needs to be dynamic, such as in loops or conditionals, allowing the programmer to manage state and respond to varying conditions.

On the other hand, a constant is a named storage location that holds a value intended to remain unchanged once it is set. This is useful for defining fixed values that should not be altered, such as mathematical constants (like π), configuration values, or other immutable data that the integrity of the program relies upon. Having constants can enhance code readability and maintainability, as they serve as a clear indication of fixed values being used throughout the program.

In summary, the defining feature that separates a variable from a constant is that a variable can be changed during execution, while a constant is defined to remain static, which is why the first choice accurately reflects this fundamental principle in programming.