Which of the following can act both as Bronsted acid and Bronsted base [MP PET 1995; MP PET/PMT 1998]

• A. \[C{{l}^{-}}\]
• B. \[HCO_{3}^{-}\]
• C. \[{{H}_{3}}{{O}^{+}}\]
• D. \[O{{H}^{-}}\]