Which Anionic Base Listed Below Would Be the Strongest Given

Multiple Choice

Which anionic base listed below would be the strongest given the corresponding acid ionization constants for their conjugate acids?

A) F ^- ; K _a(HF) = 6.8×10 ^{- 4}
B) CH₃COO ^- ; K _a(CH₃COOH) = 1.8×10 ^{- 5}
C) IO₃^{1 -} ; K _a(HIO₃) = 1.6×10 ^{- 1}
D) NO₂^{1 -} ; K _a(HNO₂) = 7.1×10 ^{- 4}