Help me with number 4

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

How do convection currents form underwater mountains?

Acivilization exists for several hundred yeaars, developing its own language. such a civilization probably has been: a. farming corn b. suffering from a lack of contact with the outside world. c. isolated by mountains or some other physical barriers. d. starving from lack of trade.