Which of the following is an example of biological control of pests using microbes?

Identify the organism based on the following characteristics:
- It grows near the root system.
- It is an effective biocontrol agent of several plant pathogens.
- It is a biological control being developed for use in the treatment of plant diseases.

Consider the following statements:
$I.$ Ladybirds and dragonflies are used to get rid of aphids and mosquitoes.
$II.$ The bacteria $Bacillus$ $thuringiensis$ $(Bt)$ are used to control butterfly caterpillars.
$III.$ $Trichoderma$ $sp.$,free-living fungi,are present in root ecosystems where they act against several plant pathogens.
$IV.$ $Rhizobium$ is a symbiotic bacterium that lives in the stem of legumes.
Which of the statements given above are correct?

Growth of water hyacinth is controlled by . . . . . . .

The insecticide obtained from the neem plant is:

Which one of the following is a genetically improved bacterium used for pollution control?