R = 4secx?? What is this equation's graph

The graph r = 4secx is a ....

ellipse? circle? parabola? hyperbola? line??

no idea. please help! 10 points for best answer.

I am assuming that we have:
r = 4secθ.

Since secθ = 1/cosθ, we see that:
r = 4secθ
==> r = 4/cosθ
==> r*cosθ = 4
==> x = 4, since x = r*cosθ.

As you can see, this is a vertical line.

I hope this helps!