Which of the following statements is true?

• A
  $CH_3CH_2S^{-}$ is both a stronger base and more nucleophilic than $CH_3CH_2O^{-}$
• B
  $CH_3CH_2S^{-}$ is a stronger base but is less nucleophilic than $CH_3CH_2O^{-}$
• C
  $CH_3CH_2S^{-}$ is a weaker base but is more nucleophilic than $CH_3CH_2O^{-}$
• D
  $CH_3CH_2S^{-}$ is both a weaker base and less nucleophilic than $CH_3CH_2O^{-}$