Which of the following is a true statement about nitrogen fixation in root nodules?
A) The plant contributes the nitrogenase enzyme.
B) The process is relatively inexpensive in terms of ATP costs.
C) Leghemoglobin helps maintain a low O2 concentration within the nodule.
D) The process tends to deplete nitrogen compounds in the soil.
E) The bacteria of the nodule are autotrophic.
