Azolla enriches rice fields with nitrogen due to its association with
Or
A free living nitrogen fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is

Options

A. Anabaena
B. Nostoc
C. Rhizobium
D. Frankia

Answer

A

Explanation

Anabaena Azollae maintains a mutually beneficial symbiotic relationship with the water fern Azolla which provides the cyanobacteria with a sage environment in exchange for nitrogen