Which one of the following is an example of carrying out biological control of pests/diseases using microbes?

1. Trichoderma species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several soil-borne plant pathogens.2. Ladybird is a biological control using an insect (predator), not a microbe.3. Nucleopolyhedrovirus is used against insects/arthropods, not specifically white rust (which is a fungal disease).4. Bt-cotton is a transgenic crop (biotechnology), not the direct application of a microbe for control in the field.