Along with the PH Scale, There Is the POH Scale

Multiple Choice

Along with the pH scale, there is the pOH scale, which indicates the level of "basicity" in a solution. Accordingly, pOH = -log[OH^-]. What is the sum of the pH and the pOH of a solution always equal to?

A) the negative of the product of the hydronium and hydroxide ions
B) the negative log of K_w, which is 14
C) The sum would equal 7, since that would be neutral for pH and pOH.
D) It is not constant because it depends on the acid/base solution in question.