Determine the Continuity of the Function $$f ( x , y ) = \frac { 9 x y } { x ^ { 2 } + y ^ { 2 } }$$

Multiple Choice

Determine the continuity of the function $$f ( x , y ) = \frac { 9 x y } { x ^ { 2 } + y ^ { 2 } }$$

A) continuous except at $( 4,0 )$
B) continuous except at $( 4,2 )$
C) continuous except at $( 0,0 )$
D) continuous except at $( 0,2 )$
E) continuous everywhere