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.