Correct group of biocontrol agents:

The correct group of biocontrol agents is option 'B', which consists of Trichoderma, Baculovirus, and Bacillus thuringiensis. These biocontrol agents play an important role in biological pest control and have been widely used in agriculture to manage pest populations.

Trichoderma:
- Trichoderma is a genus of fungi that includes several species known for their biocontrol properties.
- It can be used as a biofungicide to control various plant pathogens, including fungal diseases like damping-off and root rot.
- Trichoderma acts as a mycoparasite, competing with pathogenic fungi for nutrients and space, thereby reducing their population and suppressing disease development.

Baculovirus:
- Baculoviruses are a group of insect-specific viruses that infect and kill insects, particularly caterpillars.
- These viruses are highly specific to their target insect species and do not harm non-target organisms, making them safe for use in biological pest control.
- Baculoviruses are commonly used as biological insecticides to control pest insects that cause significant damage to agricultural crops.

Bacillus thuringiensis:
- Bacillus thuringiensis (Bt) is a soil bacterium that produces crystal proteins known as Cry toxins.
- These toxins are toxic to many insect pests, including caterpillars, mosquitoes, and beetles.
- Bt toxins have been used in the production of genetically modified crops, such as Bt cotton and Bt corn, to confer resistance against specific insect pests.
- When insects feed on these Bt crops, they ingest the Cry toxins, leading to insect death.

These biocontrol agents offer several advantages over chemical pesticides. They are environmentally friendly, pose minimal risk to non-target organisms, and do not leave behind harmful residues. Additionally, they can be used as part of an integrated pest management (IPM) approach, which combines various pest control strategies to achieve effective and sustainable pest management.

Overall, the correct group of biocontrol agents, Trichoderma, Baculovirus, and Bacillus thuringiensis, provides effective and sustainable solutions for managing pest populations in agriculture.