The PH of a 0

The pH of a 0.10 M solution of a weak base is 9.82. What is the K_b for this base?

A) 6.6 × 10^{- 4}
B) 2.0 × 10^{- 5}
C) 2.1 × 10^{- 4}
D) 4.3 × 10^{- 8}
E) 8.8 × 10^{- 8}