A laboratory stock solution of 0.500 M HCl is prepared for titration. First, 10.0 mL of the stock acid is diluted with distilled water to a final volume of 250.0 mL. Then 50.0 mL of the diluted acid is titrated with 0.100 M NaOH. What volume of the base is needed to reach the equivalence point?
a) 5.0mL
b) 10.0mL
c) 25mL
d) 2.0mL