The trend is that, the larger the value of pKb, the smaller the extent of dissociation. The smaller the extent of dissociation, the less basic (and more acidic) the solution is.
pKb is equal to -log(Kb). Let's compare, just for comparison, Kb = 0.1 and Kb = 0..9
pKb = -log(0.1) = 1
pKb = -log(0.9) = 0.045
This means that the smaller the Kb, the larger the pKb. Consequently, the larger the pKb, the less basic or more acidic the solution is. That would be pH 8.2.
The answer is C.
