What happens to the nitrogen at W?
a
Its usable form is bonded with other molecules in the atmosphere.
b
Its usable form is inhaled and turned into proteins by the rabbit.
c
Its unusable form is directly transferred up the tree roots.
d
Its unusable form is converted into a form that is usable by bacteria in the soil.
d
Its unusable form is converted into a form that is usable by bacteria in the soil.