For EDTA titrations, the analyte solution and the titrant solution are both buffered at the same pH for which of the following reasons?
I. The conditional formation constant is affected by pH.
II. The fraction of EDTA in the fully deprotonated Y4− form varies with pH.
III. When EDTA reacts to form a metal complex, H+ is a product in most cases.
(A)I only (B)I and II only (C)I and III only (D)I, II, and III
D