Which statement about the human resources and culture of the sahel is not true?
farming is done much as it has been done in ancient times.
there are few people today whose ancestors lived in ancient empires.
some leaders in the sahel have brought democracy to their country.
ethnic groups are known for their work in jewelry and wood.

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

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

In the following diagram, four different index fossils are labeled: which of the labeled fossils comes from the oldest organism? a b c d