**Discuss the continuity of the function** [ f(x, y, z) = \frac{61}{\sqrt{x^2 + y^2 + z^2}} ] **Options:** * ○ continuous everywhere * ○ continuous except where (x^2 + y^2 + z^2 < 1) * ○ continuous except where (x^2 + y^2 + z^2 > 1) * ○ continuous except where (x^2 + y^2 + z^2 > 0) * ○ continuous except at ((0, 0, 0))