1. The problem asks us to identify which of the given options represent exponential functions. 2. An exponential function has the form $$f(x) = a^x$$ where the base $$a$$ is a positive constant $$a > 0$$ and $$a \neq 1$$, and the exponent is the variable $$x$$. 3. The graph of an exponential function typically shows rapid growth or decay and passes through the point $$(0,1)$$ since $$a^0 = 1$$. 4. To determine which option is exponential, you would need to check if the variable is in the exponent position and the base is a positive constant not equal to 1. 5. Without explicit functions provided for each option, the general rule is: if the function looks like $$y = a^x$$, it is an exponential function. 6. Therefore, the option which matches this form is the exponential function.