At What Points Is the Given Function Continuous?
-F(x, Y) $\neq$

Multiple Choice

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

A) All (x, y) $\neq$ (0, 0)
B) All (x, y) $\neq$
C) All (x, y) such that x + y $\neq$ , where n is an integer
D) All (x, y)