Option B: 4 : 25
If volume ratio = 8 : 125, then side ratio = $\sqrt[3]{8} : \sqrt[3]{125}$ = 2 : 5. Surface area ratio = $2^2 : 5^2$ = 4 : 25.
Key concept: Volume of cube $\propto a^3$ and surface area $\propto a^2$. Find the cube root of the volume ratio to get the side ratio, then square it for the surface area ratio. Don't confuse volume ratio directly with surface area ratio.