Match List-I with List-II. List-I List-II (A) Trichoderma (I) Free-li…

The correct answer is Option (4) → A-II, B-IV, C-I, D-III

(A) Trichoderma — this matches (II) Biocontrol agent of plant pathogens. Trichoderma species are free-living fungi of the root ecosystem that act against several plant pathogens.

(B) Penicillium notatum — this matches (IV) Source of an antibiotic. Alexander Fleming found that this mould makes a chemical that stopped Staphylococci from growing, and he named it Penicillin after the mould.

(C) Azospirillum — this matches (I) Free-living nitrogen-fixing bacterium. Like Azotobacter, it fixes atmospheric nitrogen while free-living in the soil, not inside root nodules.

(D) Oscillatoria — this matches (III) Nitrogen-fixing cyanobacterium. It is a cyanobacterium (blue-green alga) that fixes nitrogen, along with Anabaena and Nostoc; such microbes are important biofertilisers in paddy fields.

NCERT Extract:
Microbes as Biocontrol Agents – “… A biological control being developed for use in the treatment of plant disease is the fungus Trichoderma. Trichoderma species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens.”
Antibiotics – “… He found out that it was due to a chemical produced by the mould and he named it Penicillin after the mould Penicillium notatum.”
Microbes as Biofertilisers – “… Other bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil. … Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen, e.g. Anabaena, Nostoc, Oscillatoria, etc.”