Which species acts as an acid in the reaction $CH_{3}COOH_{(aq)} + H_{2}O_{(l)} \rightleftharpoons H_{3}O^{+}_{(aq)} + CH_{3}COO^{-}_{(aq)}$?

• A
  $CH_{3}COOH$ and $H_{3}O^{+}$
• B
  $H_{2}O$ and $CH_{3}COO^{-}$
• C
  $CH_{3}COOH$ and $CH_{3}COO^{-}$
• D
  $H_{3}O^{+}$ and $H_{2}O$