Transform the given rectangular equation into a polar equation.
$y^2=117x$

$r=\frac{117\sin \theta }{{\cos }^2\theta }$

$r=117{\cos }^2\theta$

$r=\frac{117}{{\sin }^2\theta }$

$r=\frac{117\cos \theta }{{\sin }^2\theta }$