Which one of the following nutrients is not available in fertilizers?

Find out the correct sentence:
$(i)$ Hybridisation means crossing between genetically dissimilar plants.
$(ii)$ Cross between two varieties is called as inter-varietal hybridisation.
$(iii)$ Introducing genes of desired character into a plant gives genetically modified crop.
$(iv)$ Cross between plants of two species is called as inter-specific hybridisation.

Why is excess use of fertilizers detrimental for the environment?

Based on the kind of biological material used,what are the two kinds of manures? How are they prepared?

Define $(i)$ Vermicompost,$(ii)$ Green manure,and $(iii)$ Biofertilizer.

How does catla differ from mrigal?