Answer
VI
Work Step by Step
We should choose VI because $r=3cos\theta$ is a circle centered at $(1.5,0)$.
Multiply $r$ to both sides, we have $r^2=3rcos\theta$, convert to rectangular coordinates, we have
$x^2+y^2=3x$ which leads to $(x-\frac{3}{2})^2+y^2=(\frac{3}{2})^2$ which is a circle centered at $(\frac{3}{2},0)$ and a radius of $\frac{3}{2}$
