I have calculated the answers to Steps A, B & C. I need help with Step D only.Please answer…

I have calculated the answers to Steps A, B & C. I need help with Step D only.
Please answer STEP D
1. When 50. mL of 0.50 M formic acid is titrated with 0.50 M sodium hydroxide, calculate the pH:
a) before any of the titrant (NaOH solution) is added, (Answer to this step is pH =2.04)
b) after 15.0 mL of the titrant has been added, (Answer to this step is pH =3.40)
c) when half of the formic acid has been neutralized, and (Answer to this step is pH =3.77)
d) at the equivalence point (be sure to account for the change in volume at each step) and select a good indicator for this titration.