BOD can be defined as

• A

  amount of ${\mathrm{CO}}_2$ consumed if all the inorganic matter in one litre of water is oxidized by bacteria.

• B

  amount of ${\mathrm{O}}_2$ consumed if all the organic matter in one decilitre of water is reduced by bacteria.

• C

  amount of ${\mathrm{O}}_2$ consumed if all the organic matter in one litre of water is oxidized by bacteria.

• D

  amount of ${\mathrm{O}}_2$ consumed if all the inorganic matter in one litre of water is oxidized by bacteria.