Which biocontrol agent(s) is/are very effective against the members of the largest phylum of the animal kingdom?

I. Baculoviruses
II. Trichoderma
III. Ladybird beetle & Dragonflies

The correct option is A I and III only
Biocontrol agents are living organisms which restrict the spread of other organisms by either consuming them or killing them (without consuming). These biocontrol agents are very selective about the organisms they target, preferably sticking to a particular group of target organisms. The largest phylum of the animal kingdom is phylum Arthropoda. It is a phylum comprising animals with jointed appendages. Class Insecta is the largest class under it.
Baculoviruses are a group of viruses that act as biocontrol agents against a variety of insects and other arthropods. Baculoviruses are regarded as natural pest management microorganism. Most of the baculoviruses of such nature belong to the genus of Nucleopolyhedrovirus.
Ladybird beetles are used effectively against aphids which are insects that feed on plant sap.
As a part of Integrated Pest Management program (IPM), dragonflies can be used to control the population and spread of insect pests such as mosquitoes. Thus ladybird beetles and dragonflies are also effective in controlling members of Phylum Arthropoda.
Fungi belonging to the genus Trichoderma are well-known for their roles against various plant fungal pathogens such as Phytophthora, Fusarium, etc., but not against the members of the phylum Arthropoda.