The EPA __________ the planting of refuges or refuge-in-the-bag for the registration and sale of Bt-crops.

The correct response emphasizes that the EPA requires the planting of refuges or the use of refuge-in-the-bag for the registration and sale of Bt-crops. This requirement is a crucial component of integrated pest management strategies aimed at delaying the development of pest resistance to Bt toxins used in these genetically modified crops.

Refuges are areas planted with non-Bt crops that serve as a habitat for pest populations that have not been exposed to Bt technology. By maintaining these populations, the overall genetic diversity of the pest population is increased, and the chances of resistant insects developing are reduced. The EPA’s regulation ensures that farmers implement this strategy effectively to prolong the effectiveness of Bt traits in the crops.

This regulatory framework is based on scientific research demonstrating that without refuges, pests could quickly adapt to and render Bt technologies ineffective. Therefore, it's essential for compliance with these agricultural practices to enhance sustainability and manage resistance in pest populations effectively.