A 2.57 g sample of an iron alloy (a mixture of iron with other metallic elements) was dissolved in hydrochloric acid to give a solution of Fe²+ ion. This solution was titrated to end point with 38.9 M HCl. What is the molarity of Fe²+ ion in the solution?

a) 0.066 M
b) 0.133 M
c) 0.266 M
d) 0.532 M