What is the first step of seafloor spreading?

A crack forms in oceanic crust.
Molten rock rises up through oceanic crust.
Molten rock solidifies at the center of the ridge.
New material pushes older rock away from the ridge.

Plants in the tundra biomes have had to adapt to live long periods of time without a. cool temperatures b. sunlight c. oxygen d. water

This phrase from the declaration of independence and its primary author thomas jefferson can be used to justify which statement? a) jefferson thought this document could be used in his defense were he put on trial for treason. b) jefferson knew that the colonists' actions would have an international impact. c) jefferson believed that a bill of rights was necessary in the new government. d) jefferson was trying to show the king that the colonists were intellectuals.

What id the primary human cause of the global warming a. storage of nuclear fuel rods b. burning of fossil fuels c. building of high-density housing d. violent conflicts over natural resources