Wolbachia method' is sometimes talked about with reference to which one of the following?

1. A

   Controlling the viral diseases spread by mosquitoes

   Controlling mosquito-borne viral disease. Wolbachia-infected Aedes reduce dengue (and related) transmission.

2. B

   Converting crop residues into packing material

   Crop residue to packing. Unrelated.

3. C

   Producing biodegradable plastics

   Biodegradable plastics. Unrelated.

4. D

   Producing biochar from thermochemical conversion of biomass

   Biochar. Unrelated.

Summary. Official key is (a). The Wolbachia method infects Aedes mosquitoes so that dengue, Zika and similar viruses replicate poorly, or so that incompatible males suppress the wild population. It is not a plastics or biochar technique.