At What Points Is the Given Function Continuous?
- $f ( x , y ) = \tan ( x + y )$

Multiple Choice

At what points is the given function continuous?
- $f ( x , y ) = \tan ( x + y )$

A) All $( x , y ) \neq \left( \frac { \pi } { 2 } , \frac { \pi } { 2 } \right)$
B) All $( x , y ) \neq ( 0,0 )$
C) All $( x , y )$ such that $x + y \neq \frac { ( 2 n + 1 ) \pi } { 2 }$ , where $n$ is an integer
D) All ( $x , y )$