The distance to the nearest star (beyond the sun) is about times the distance to neptune?

The distance to the nearest star is about 8.92x10^5 times the distance to Neptune. The nearest star to earth is is Proxima Centauri at about 4.24 light years. The average distance of Neptune is 2.795 billion miles. So we need to convert those two measurements to use the same units. A light year is about 5.879x10^12 miles. So 5.879x10^12 * 4.24 = 24.92696 x 10^12 = 2.492696x10^13 miles Now divide the distance to the nearest star by the distance to Neptune. 2.492696x10^13 / 2.795x10^9 = 0.891841 x 10^4 = 8.91841x10^5 Since the figures we have are really rough (only know the distance to Proxima Centauri to 3 significant digits, round the result to 3 significant digits as well, giving an estimate of 8.92x10^5

The answer would be (c), mass extinctions