Which of the following statements is correct with regard to biocontrol agents ?
• A
Ladybird and dragonflies are used to get rid of aphids and mosquitoes respectively.
• B
Bacillus thuringiensis bacteria are used to control butterfly caterpillars.
• C
Trichoderma species are used to control several plant pathogen.
• D
All of these

#### Solution

Ladybird and dragonflies are used to get rid of aphids and mosquitoes respectively. Bacillus thuringiensis bacteria are used to control butterfly caterpillars. Trichoderma species are used to control several plant pathogen..
So, the correct option is 'All of these'