A solution containing NaOH and Na2CO3 is titrated against 0.1 M HCl solution using phenolphthalein indicator. At the equivalence point
a. Both NaOH and Na2CO3 are completely neutralized
b. Only NaOH is completely neutralized
c. Only Na2CO3 is completely neutralized
d. NaOH completely and Na2CO3 upto the stage of NaHCO3 are neutralized.