Root nodules for nitrogen fixation of a non-leguminous tree possess

In leguminous plants,root nodules are formed by which of the following?

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.

$Frankia$ is free-living in soil,but as symbionts,can fix atmospheric nitrogen.

Assertion : Nitrogen-fixing enzyme in legume root nodules functions at low oxygen concentration.
Reason : Low oxygen concentration is provided by leghaemoglobin.

Identify the following process from the diagram.