Use of biofertilizers as a nutrient source is practised in __________.

The correct answer is Option (3) → Organic farming

Option (3) Organic farming — Correct. Organic farming avoids chemical fertilisers and pesticides. It uses biofertilisers (bacteria, fungi and cyanobacteria) to enrich the nutrients of the soil.

NCERT Extract:
Microbes as Biofertilisers – “… With our present day life styles environmental pollution is a major cause of concern. The use of the chemical fertilisers to meet the ever-increasing demand of agricultural produce has contributed significantly to this pollution. Of course, we have now realised that there are problems associated with the overuse of chemical fertilisers and there is a large pressure to switch to organic farming – the use of biofertilisers.”