If x + y + z = 0, then the value of (x2 + y2 + z2) ÷ (z2 - xy) is:

Answer: Option B

$$\begin{array}{rl}& x+y+z=0\\ & \text{Let }x=y=1\\ & z=-2\\ & \frac{x^2+y^2+z^2}{z^2-xy}\\ & =\frac{1+1+4}{4-1}\\ & =2\end{array}$$