What type of measures are used in response to an existing pest problem?

The correct choice is remedial measures, which are specifically designed to address and resolve an existing pest problem. When pests are already present and causing issues, remedial actions are necessary to eliminate or control the infestation. These may include targeted pest control treatments, such as insecticides or traps, and strategies to repair the environment to prevent further infestation.

Remedial measures differ from preventive measures, which focus on stopping pests before they become a problem, and mitigative measures, which aim to reduce the impact of pests without necessarily addressing the infestation directly. Corrective measures, while related to fixing problems, can be broader and may not specifically pertain to pest control scenarios. Thus, the emphasis on rectifying an immediate pest issue clearly identifies remedial actions as the appropriate response in this context.