9. A 0.050 M solution of the salt NaB has a pH of 9.00. The [OH-] of a 0.010 M solution of HB is thus __________M.
(A)4.6 × 10-11
(B) 4.5 × 10-6
(C)3.0 × 10-9
(D) 2.2 × 10-4
(E)2.2 × 10-5