Which of the following are rational functions? Select all that apply.
$f(x)=\frac{x^{5}-x^{3}+4}{x^{2}+15 x-2}$
$f(x)=\frac{1}{x}$
$f(x)=\frac{2^{x}}{5}$
$f(x)=\frac{x^{2}+5}{x}$
$f(x)=\frac{\log (x)}{2 x+5}$

Step 1 ：A rational function is a function that can be written as the ratio of two polynomials. The numerator and the denominator are both polynomials. The denominator cannot be zero.

Step 2 ：Looking at the functions given, we can see that \(f(x)=\frac{x^{5}-x^{3}+4}{x^{2}+15 x-2}\), \(f(x)=\frac{1}{x}\), and \(f(x)=\frac{x^{2}+5}{x}\) are rational functions because they can be written as the ratio of two polynomials.

Step 3 ：\(f(x)=\frac{2^{x}}{5}\) and \(f(x)=\frac{\log (x)}{2 x+5}\) are not rational functions because \(2^{x}\) and \(\log (x)\) are not polynomials.

Step 4 ：\(\boxed{\text{The rational functions are } f(x)=\frac{x^{5}-x^{3}+4}{x^{2}+15 x-2}, f(x)=\frac{1}{x}, \text{ and } f(x)=\frac{x^{2}+5}{x}}\)