Final answer:
Parasitic wasps are a type of biological control used to reduce roach populations by laying eggs inside their bodies, which then lead to the pest's death.
Step-by-step explanation:
A type of biological control for roaches is b) parasitic wasp. Biological control involves using predators, parasites, or disease agents to reduce pest populations. Parasitic wasps, which are natural enemies of various insect species, lay their eggs inside the bodies of pests such as caterpillars.
When the wasp larvae hatch, they consume the host from the inside, leading to the pest's death. This method of pest control aims to manage pest populations without the adverse effects associated with chemical pesticides, such as impacts on non-target species or human health.