Microbial conversion of nitrate into chemical nitrogen is called:

Correct option is A

✅ (a) Denitrification: • Denitrification is the microbial process where nitrate (NO₃⁻) is reduced to gaseous nitrogen (N₂ or N₂O). • Carried out by anaerobic bacteria like Pseudomonas, Bacillus, especially in waterlogged soils. • It removes nitrogen from the soil, releasing it into the atmosphere.
❌ (b) Nitrate reduction: • A broader term; may not always convert it to gaseous nitrogen.
❌ (c) Nitrogen fixation: • Opposite process – converts atmospheric N₂ into ammonia, not nitrate.
❌ (d) None of these: • Incorrect, as (a) is accurate.