Which one of the following is wrong statement?

• A

  Anabaena and Nostoc are capable of fixing nitrogen in free-living state also
• B

  Root nodule forming nitrogen fixers live as aerobes under free-living conditions
• Correct answer
  C

  Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins
• D

  Nitrosomonas and Nitrobacter are chemoautotrophs

Hence, the correct answer is option: 'C'.