Mutagens are: a)
chemical factors like radiomutation
b)
external factors responsible for tissue changing
c)
factors responsible for formation of mutation in the cell
d)
those which are responsible for formation induced mutation
e)
factors which act against the formation of mutation
f)
chemical factors like yperite or coffin
g)
genes responsible for formation of mutation
h)
physical factors like ionizing radiation

c)

factors responsible for formation of mutation in the cell

Explanation:

hope this helps

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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