Expenditure of water molecules for fixing a specific amount of carbon dioxide in ${\mathrm{C}}_3$ plants is:

• A

  Half as that of ${\mathrm{C}}_{4 }$plants

• B

  Double as that of ${\mathrm{C}}_{4 }$plants

• C

  Triple as that of ${\mathrm{C}}_{4 }$plants

• D

  Same as that of ${\mathrm{C}}_{4 }$plants