In Changing from Cartesian to Spherical Coordinates $\frac { \partial r } { \partial x }$

Multiple Choice

In changing from Cartesian to spherical coordinates, $\frac { \partial r } { \partial x }$ becomes

A) $\sin \phi \sin \theta$
B) $\sin \phi \cos \theta$
C) $\cos \phi \sin \theta$
D) $\cos \phi \cos \theta$
E) $\sin \phi$