The sun is a star but the earth is a planet why

Gold is not now being extracted from seawater. why not? a. it would be too disruptive to marine life to develop any marine mineral resources b. there is no gold in seawater c. we don't know how to extract minerals from seawater d. it would be too costly and difficult to separate the small amount of gold from the very large amounts of halite and other minerals

How many structures do prokaryotic cells have in common with the eukaryotic cells? a. 2b. 3c. 4d. 5

b) is there any ordinal sense to zip codes? in other words, does a larger zip code tell you anything about a location compared to a smaller zip code?