A 200 ML Sample of Lactic Acid (Monoprotic with K _a

A 20.0 mL sample of lactic acid (monoprotic with K _a = 1.37×10 ^{- 4}) requires 30.0 mL of 0.200 M NaOH for titration to the equivalence point. What is the concentration of the lactic acid solution?

A) 0.120 M
B) 0.200 M
C) 0.300 M
D) 6.00×10 ^{- 3} M
E) cannot be found without the molar mass of lactic acid.