Find the Intervals Where $f(x)=\frac{\log 9 x}{x}$ Is Increasing and Where It Is Decreasing

Multiple Choice

Find the intervals where $f(x) =\frac{\log 9 x}{x}$ is increasing and where it is decreasing.

A) increasing: $(9 e, \infty)$ , decreasing: $(0,9 e)$
B) increasing: $\left(0, \frac{e}{9}\right)$ , decreasing: $\left(\frac{e}{9}, \infty\right)$
C) increasing: $(90, \infty)$ , decreasing: $(0,90)$
D) increasing: $\left(0, \frac{9}{10}\right)$ , decreasing: $\left(\frac{9}{10}, \infty\right)$