Which of the following is an example of a bio-pesticide?

Bacillus thuringiensis (Bt) is an example of a bio-pesticide because it is derived from a naturally occurring bacterium. This bacterium produces a protein that is toxic to certain insects, specifically caterpillars, and is utilized in pest management as a biological control agent. Organic farmers and those seeking environmentally friendly pest management practices often favor bio-pesticides like Bt because they target specific pests while minimizing harm to non-target organisms, humans, and the environment.

In contrast, the other options listed are synthetic chemical pesticides. Chlorpyrifos is a broad-spectrum insecticide that affects a wide range of insects, while Roundup, which contains glyphosate, is a glyphosate-based herbicide primarily used to control weeds. Malathion is another synthetic insecticide used against a variety of pests. These chemical pesticides do not derive from natural biological materials in the same way that bio-pesticides do, which distinguishes Bt as a more targeted and often safer option for certain pest management scenarios.