Which group of gases is favorable for fruit ripening?

• A
  $80\% CO_2$ and $20\% CH_2$
• B
  $80\% CH_2$ and $20\% CO_2$
• C
  $80\% C_2$ and $20\% O_2$
• D
  $80\% C_2H_4$ and $20\% CO_2$