5. A solution contains 0.2M NH4OH and 0.2M NH4CI. If 1.0 mL of 0.001 M HCl is added to it. What will be the [OH^-] of the resulting solution [Kb = 2x10^-5] ?

A. 2x10^-5

B. 2x10^-3

C. 5x10^-10

D. None of these