The graph above describes the energy change that results from a chemical reaction. To what is that energy change due?
A a reaction that requires ATP
B a reaction that requires ADP
C the breakdown of ATP to ADP and phosphate
D the synthesis of ATP from ADP and phosphate

i can't see the full page, therefore, can't answer it

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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well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."