Symbiotic nitrogen fixation in root nodules of some legumes is caused by

Mark the correct sequence of steps for the development of root nodules in legumes:
$a.$ Formation of infection thread.
$b.$ Division of cortical and pericyclic cells.
$c.$ Curling of root hairs.
$d.$ Leghaemoglobin synthesis.

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.

Leghemoglobin is found in which one of the following organisms?

Which bacteria live symbiotically on the root system of leguminous plants?

Which of the following statements is correct regarding nitrogen fixation in legumes?