A pipe with a rectangular cross$-$section has width $\backslash ($ w $\backslash )$ and height $\backslash ($ h $\backslash ).$ Water leaves the pipe with speed $\backslash ($ v $\backslash )$ and fills a pool with volume $\backslash ($ V $\backslash ).$ Which of the following expressions is equal to the time it takes the pool to be completely filled?

$\backslash [$

$($

$\backslash ]$

$\backslash [$

$\backslash$frac$\{1\}\{$w h v$\}$

$\backslash ]$