Which action must landlords take immediately upon being notified of a pest issue?

The correct choice emphasizes the responsibility of landlords to address pest issues promptly. When landlords are notified of a pest problem, it is crucial that they take immediate action to control the infestation. This is aligned with health and safety standards as well as tenant rights, as pests can pose serious health risks and negatively impact living conditions. Immediate response not only helps in rectifying the situation but also demonstrates the landlord's commitment to maintaining a safe and habitable environment for tenants.

Taking necessary actions to control the infestation can include hiring pest control professionals, conducting inspections, and implementing preventive measures. This proactive approach is essential in ensuring that the issue is managed effectively and does not escalate, which could lead to more significant problems for both tenants and the property.

In contrast, seeking permission from tenants before acting could delay the resolution and is not typically required, as landlords have an obligation to maintain the premises. Waiting until the end of a pest season to address the issue could exacerbate the problem, as infestations may worsen over time. Documenting tenant complaints is certainly important for record-keeping and legal purposes, but it does not resolve the pressing issue of the infestation itself. Therefore, the requirement for landlords is to take decisive action to control the pests without unnecessary delays.