Are formed when one crustal plate is forced under another.
a. rift zones
c. mid-ocean ridges
b. trenches
d. continental shelves

Nuclear experimentation is a major global issue that affects relationships between countries. describe why countries try to limit the testing of nuclear weapons.

Which of these is least likely to be an adaption? a. a mouse digs a hole to hide from predators. b. a snake bites its prey to deliver it deadly venom. c.a jackrabbit has large ears that it release body heat. d.a parrot learns to say its owner's name.

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.