Which answers choice best describes john dalton‘s contribution to automatic theory

I think. it's a because that is a fact that really did happen

The answer for this is a

(no3)⁻n has oxidation number x,o has oxidation number -2.(x*1 -2*3) charge of the nitrate ion, and we know that charge of the nitrate ion =-1.so,(x*1 -2*3) =-1x-6=-1x=+5answer a. +5.