During the titration of a monoprotic weak acid with a strong base, which statement best describes the solution when exactly one-half of the volume of base required to reach the equivalence point has been added?
a) The pH of the solution is exactly 7.00 at 25∘C. (common neutral-solution assumption)
b) The pOH of the solution is numerically equal to the pKa of the acid.
c) The pH of the solution is numerically equal to the pKa of the acid.
d) The concentration of conjugate base is twice the concentration of the remaining acid.