Express rectangular coordinates in terms of cylindrical coordinates.
A) x = r cos θ, y = r sin θ, z = z
B) r = √(x² + y²), θ = tan(-1)(y/x), z = z
C) x = r sin θ, y = r cos θ, z = z
D) r = √(x² + y²), θ = tan(-1)(x/y), z = z