$KO_2C-CH_2-CH_2-CO_2K \xrightarrow{\text{electrolysis}} (A) \text{ (major)}$ (Kolbe electrolysis method). The product $(A)$ of the reaction is:

• A
  $CH_3-CH_3$
• B
  $CH_2=CH_2$
• C
  $CH_3-CH=CH_2$
• D
  \text{none of these}