1. Let's understand what an exponential function is. 2. An exponential function has the form $$f(x) = a^x$$ where $$a$$ is a positive constant not equal to 1. 3. To classify how the function behaves as a relation, consider whether it pairs each input $$x$$ with exactly one output value. 4. For exponential functions, each input $$x$$ corresponds to one unique output $$a^x$$; no input maps to multiple outputs. 5. Hence, an exponential function is a function (each input has one output), so it cannot be many-to-one or one-to-many based on this definition. 6. Finally, exponential functions are one-to-one functions because if $$a^x = a^y$$ then $$x = y$$ due to the properties of exponential functions. 7. Therefore, the correct classification is: **A one-to-one function**.