Ill give a Brainliest if it is right The pictures below show a bottle made of plastic and a block made of concrete.

Which of these statements is correct about plastic and concrete?
A)Both plastic and concrete are minerals because they are natural, solid materials.
B)Both plastic and concrete are not minerals because they are made by humans.
C)Plastic is a mineral because it has a definite crystal structure but concrete is not a mineral because it is organic.
D)Plastic is not a mineral because it is not formed under the ground but concrete is a mineral because it has a definite composition.

Neither of these are minerals, B.

Its not A because, they are not natural materials but instead made up of natural materials, like a rubber tree.

Its not C because, like I said, plastic is made from rubber trees, this garentees it doesnt have a crystal structure.

Its not D because, concrete is not a mineral and has indefinite composition.

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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