Find the Center and Radius of the Sphere $x ^ { 2 } + y ^ { 2 } + z ^ { 2 } - 12 z = 0$

Multiple Choice

Find the center and radius of the sphere. $x ^ { 2 } + y ^ { 2 } + z ^ { 2 } - 12 z = 0$

A) center: (0,0,6) ;radius: 6
B) center: (0,0,6) ;radius: 36
C) center: (0,0,-6) ;radius: 6
D) center: (0,0,0) ;radius: 0
E) center: (0,0,0) ;radius: 36