When Changing from Cartesian to Spherical Coordinates $\frac { \partial \phi } { \partial x } =$

Multiple Choice

When changing from Cartesian to spherical coordinates, $\frac { \partial \phi } { \partial x } =$

A) $- \sin \phi / ( r \sin \theta )$
B) $\sin \phi / ( r \sin \theta )$
C) $- \cos \phi / ( r \sin \theta )$
D) $\cos \phi / ( r \cos \theta )$
E) $\sin \phi / ( r \cos \theta )$