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

• A. $r=\frac{117\sin\theta}{\cos^2\theta}$
• B. $r=117\cos^2\theta$
• C. $r=\frac{117}{\sin^2\theta}$
• D. $r=\frac{117\cos\theta}{\sin^2\theta}$

Answer: (D)