The risk practitioner's best recommendation when one of an organization's key IT systems cannot be patched because the patches interfere with critical business application functionalities is to identify additional mitigating controls, as they may reduce the likelihood or impact of the vulnerabilities being exploited, and align the residual risk with the risk tolerance and appetite of the organization. The other options are not the best recommendations, as they may not address the risk adequately, or may introduce unacceptable consequences, such as disrupting the businessoperations, changing the risk strategy, or accepting excessive risk. References = CRISC Review Manual, 7th Edition, page 111.