How did volcanoes change Earth in the first two billion years? O A. They outgassed water vapor and carbon dioxide into the
atmosphere.
O B. They caused plate movement that arranged the continents we
have today.
O C. They gradually heated the planet.
O D. They created sedimentary rock.

The volcanoes provided, on the surface of the earth, the heat, water and the powerful cocktail of organic compounds (hydrogen sulphide, arsenic) that are at the beginning of life. ... The intense performance of CO2 (carbon dioxide) volcanoes allowed the Earth's heat to fix itself permanently in our atmosphere.

Explanation:

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: