In many cases, it can be easier to describe a curve with Cartesian coordinates. Other times, polar coordinates may be easier. Below, four curves are described in words, and four choices of equations are given -- two are in Cartesian form and two in polar form. Match each description with the correct curve.

A. A line through the origin that makes an angle of $\pi/6$ with the positive $x$-axis.
B. A vertical line through the point (3, 3).
C. A circle with radius 5 and center (2, 3).
D. A circle centered at the origin with radius 4.

1. $\theta=\pi/6$
2. $(x-2)^2+(y-3)^2=25$
3. $x=3$
4. $r=4$