Let $r(x)=ta{n}^3(x).$ Which of the following best describes its fundamental algebraic structure?

Composition. A composition $f(g(x))$ of basic functions

Sum. A sum $f(x)g(x)$ of basic functions

Product. A product $f(x)*g(x)$ of basic functions

Quotient. A quotient $f\frac{x}{g}(x)$ of basic functions

Determine $f(x)$ and $g(x).$

$f(x)=$

$g(x)=$