What is the primary function of biofertilizers?

Which of the following is the most suitable fertilizer for paddy fields?

Farmers have reported over $50\%$ higher yields of rice by using which of the following biofertilizer?

Mycorrhiza is a symbiotic association between which of the following?
$(i)$ Fungi of the genus $Glomus$
$(ii)$ $Rhizobium$
$(iii)$ Root nodules of leguminous plants
$(iv)$ Cyanobacteria
$(v)$ Roots of higher plants
$(vi)$ Paddy fields

Identify the correct statements regarding mycorrhiza:
$(1)$ Many members of the genus $Glomus$ form mycorrhiza.
$(2)$ It is responsible for all mineral absorption from the soil.
$(3)$ Such associations show benefits against drought and salinity in plants.
$(4)$ Mycorrhiza is a symbiotic association between fungi and roots of higher plants.

What is the function of the fungus $Glomus$ as a symbiont?