What type of pesticides are living agents used to control specific pathogens?

The correct answer is biological. Biological pesticides, also known as biopesticides, include living agents such as bacteria, fungi, viruses, and other microorganisms that can control specific pests or pathogens. These agents can work through various mechanisms, such as parasitism, predation, or the production of toxins that specifically target unwanted organisms while minimizing impact on non-target species. This specificity makes biological pesticides a valuable tool in integrated pest management strategies, as they often have reduced environmental impacts compared to synthetic chemical pesticides.

Biorational pesticides refer to products that are derived from natural materials and are designed to be less harmful to non-target organisms than conventional chemicals, but they do not necessarily involve living agents. Chemical pesticides, on the other hand, are synthetic substances used for pest control, and selective pesticides refer to those that are designed to target specific pests while leaving others unharmed. These choices do not focus on the living agents aspect that is central to the correct answer.