Let f(x) = (|__x__|)/(x^2 + 1) where |__x__| denotes the greatest integer less than or equal to x. Then?

A. f is continuous for all x.
B. f is continuous only when x is an integer.
C. f is continuous only when x is not an integer.
D. f is not continuous at any value of x.

I know that the function is continuous at every point except at x^2 +1 = 0
But x^2 = -1 is not a real number.
Please help.