The titration of a 50.0 mL solution of the monoprotic bromoacetic acid (pKa = 3) takes 10 ml of 0.01 mol L-1 NaOH to reach the stoichiometric point. What was the initial concentration of bromoacetic acid?

A) 0.02 mol/L
B) 0.01 mol/L
C) 0.002 mol/L
D) 0.001 mol/L

mL acid x M acid = mL base x M base.