Suppose that the evolving star is the same size as our Sun at the start of the animation. The white dwarf, meanwhile, is only about as large as the Earth—even though it may have two-thirds or three-quarters as much mass as the evolving star! Which one of the following expressions would best represent the ratio of the two stars' diameters? 

Note: The Sun's radius is about 696,000 km, or 6.96 ✕ 105 km, whereas the Earth's radius is about 6,380 km or 6.38 ✕ 103 km.