Choose the incorrect sentence.

• A
  The enzyme nitrogenase is highly sensitive to molecular oxygen.
• B
  Most plants can assimilate nitrate as well as ammonium ions; the latter is quite toxic to plants and hence cannot accumulate in them.
• C
  To protect nitrogenase enzymes,the nodule contains an oxygen scavenger called leg-haemoglobin.
• D
  The ammonia synthesis by nitrogenase requires a very high input of energy.