Identify the Equation (Written in Terms of Cylindrical or Spherical $a = 2$

Multiple Choice

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

A) $a = 2$
B) $r = 2$
C) $z = \frac { r ^ { 2 } } { 2 }$
D) $z = 2 r ^ { 2 }$
E) $\beta = 2 \sec \phi$