The free-living fungus Trichoderma can be used for:
a. killing insects
b. biological control of plant diseases
c. controlling butterfly caterpillars
d. producing antibiotics
The answer is option (b) biological control of plant diseases.
Explanation:
Trichoderma is a fungus used to treat plant diseases caused by soil-borne pathogens. Trichoderma inhibits the growth of fungi that harm the plants.