Ocean trenches are formed when
a) two oceanic plates slide past each other.
b) an oceanic plate goes under another oceanic plate.
c) two oceanic plates grind past each other along transform faults.
d) two oceanic plates hit each other causing both plates to rise up.

12) several teeth were found in an area of flat land covered with trees and plants. the teeth were examined by a paleontologist, and it was determined that the teeth came from a shark. they found many other shark teeth in this area. however, the people who discovered the teeth were puzzled, because there was no source of water near where the fossils were found. what is the paleontologist's best explanation for why the teeth were found in this area? a) sharks used to live on flat land. b) this area was once covered with salt water. c) this area was once covered with freshwater. d) someone buried the shark teeth deep in the ground.