The largest set on which the functionfxy116-x2-y2is

Question

The largest set on which the functionf(x,y)=1/(16-x2-y2)is continuous is?
A. The interior of the circle x2+y2=16 
B. The exterior of the circle x2+y2=16 
C. All of the xy-plane except the circle x2+y2=16 
D. All of the xy-plane 
E. The interior of the circle x2+y2=16, plus the circle