In which of the following are root nodules found?

Identify the $A$ to $D$ correctly in the given diagram of root nodule development and choose the correct option accordingly.

Arrange the stages of root nodule formation in the correct sequence:
$I-$ Infection thread is produced.
$II-$ Bacteria are carried to the cortex of the root.
$III-$ Bacteria attach to the root hair.
$IV-$ Bacteria are released from the thread into the cells.
$V-$ Differentiation into nitrogen-fixing cells occurs.

With reference to the root nodules shown in the following diagram,select the correct option.

The amount of nitrogen in nature is fixed by .....

Which of the following is correct regarding nitrogen fixation by legumes? They fix nitrogen through: