Which genus of fungi is used to form mycorrhiza?

Which of the following is used as biofertiliser?
$I.$ Cyanobacteria
$II.$ Yeast
$III.$ Symbiotic bacteria
$IV.$ Free living bacteria
Choose the correct option.

The common nitrogen fixer in paddy fields is . . . . . . .

Which one is a green manure or biofertilizer?

Anabaena has an immense potential as a:

Which of the following serve as biofertiliser in paddy fields?