3.6 rounded to the nearest whole number

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

Which factors add to the greenhouse effect and are caused by human activities?

Based on the information in the graph, what can you conclude about humans in the world in general?