Answer: B is the answer i believe.
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M1 = 17.45 M
M2 = 0.83 M
V2 = 250 ml
M1. V1= M2. V2
V1 = (M2. V2)/M1 = (0.83× 250)/ 17.45= 11.89 ml
The final step in a typical titration, that is here an acid base one would be to finally find the concentration of your unknown substance whether that be the acid or the base. The other steps are used before this to come to the correct calculation and conclusion.