I have a test please help me with this one

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 age groups shows the graestest diferrence between males and females

In order from largest to smallest what are earths five main oceans