How can drought be triggered by the physical conditions

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

What statistics are to determine the development of a nation?

The graph below plots the temperature and luminosity of stars on the main sequence.