C. 0.5
This is the answer.
(assuming that the D option is 1, if it is 0.1 then the answer is 0.1)
[tex]0.5[/tex]
Explanation:
As you know that decreasing in the concentration of OH- (i.e., 14, 13, 12, 11,..) makes to increase in the concentration of H+ ions (5,4,3,2,1).
