And so we would rule this one out. So let's think about f of x equals e to the x. It is defined for all real numbers, and as we'll see, most of the common functions that you've learned in math, they don't have these strange jumps or gaps or discontinuities. Some of them do, functions like one over x and things like that, but things like e to the x, it doesn't have any of those. We could graph e to the x. E to the x looks something like this. It's defined for all real numbers. There's no jumps or gaps of any kind, and so this f of x is continuous for all real numbers, and f only.