Which sentence about an ocean current is correct? A) Upwelling is caused by winds that blow on the ocean's surface.
B) Upwelling moves water horizontally.
C) Surface currents are caused by differences in water density.
O D) Surface currents move vertically through the water.

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes