The most important information to include when reporting the effectiveness of risk management to senior management is the changes in residual risk levels against acceptable levels, as it indicates how well the risk management process and activities have reduced the risk exposure and impact to the level that is aligned with the risk tolerance and appetite of the organization. The other options are not the most important information, as they are more related to thedrivers,factors, or outcomes of risk management, respectively, rather than the effectiveness or value of risk management. References = CRISC Review Manual, 7th Edition, page 109.