The information security manager's best course of action is to report the findings of the risk assessment to the key stakeholders, such as senior management, business owners, and regulators. This will ensure that the stakeholders are aware of the potential impact of the risk and can make informed decisions on how to address it. The other options are possible actions to take after reporting the findings, but they are not the best course of action in this scenario. References = CISM Domain 2: Information Risk Management (IRM) [2022 update] (section: Information Risk Response) and CISM ITEM DEVELOPMENT GUIDE - ISACA (page 6, item example 2)