Given two similar spheres that have this scale factor:
You need to remember that, by definition:
- Two solids are similar if the measures of their corresponding edges are in proportion and their corresponding angles are congruent.
- The ratio of the surface areas of two similar solids is the square of the scale factor between them.
Therefore, in order to find the ratio of the surface areas of these similar spheres, you need to square the scale factor:
Hence, the answer is: Third option.