Describe the graph of the equation. r = 4 sin 6t i – 4 cos 6t j O It is a parabola in the xy-plane, with vertex at the origin. O It is an ellipse in the xy-plane, centered at the origin, with major axis of length 4. O It is a circle of radius 4 in the xy-plane, with center at the origin. O It is a circle of radius 6 in the xy-plane, with center at the origin. O It is a circle of radius 4 in the xy-plane, with center at the point (6, 6).