Identify the Equation (Written in Terms of Cylindrical or Spherical $\phi = \frac { \pi } { 6 }$

Multiple Choice

Identify the equation (written in terms of cylindrical or spherical coordinates) of the following graph.

A) $\phi = \frac { \pi } { 6 }$
B) $r = \frac { \pi } { 6 }$
C) $\beta = \frac { \pi } { 6 }$
D) $\theta = \frac { \pi } { 6 }$
E) $z = r \cos \frac { \pi } { 6 }$