Three 15.0-mL acid samples—0.10 M HA, 0.10 M HB, and 0.10 M H₂C—are all titrated with 0.100 M NaOH. If HA is a weak acid, HB is a strong acid, and H₂C is a diprotic acid, which statement is true of all three titrations?

a) All three titrations have the same pH at the first equivalence point.

b) All three titrations have the same initial pH.

c) All three titrations have the same final pH.

d) All three titrations require the same volume of NaOH to reach the first equivalence point.