During a titration the following data were collected. A 20 mL portion of an unknown monoprotic acid solution was titrated with 2.0 M KOH. It required 60 mL of the base to neutralize the sample. What is the molarity of the acid?
a. ) 6.0
b. ) 0.60
c. ) 3.0
d. ) 0.30
e. ) 0.67