The information security manager’s primary focus during the development of a critical system storing highly confidential data should be ensuring the amount of residual risk is acceptable. Residual risk is the level of cyber risk remaining after all the security controls are accounted for, any threats have been addressed and the organization is meeting security standards. It’s the risk that slips through the cracks of the system. For a critical system storing highly confidential data, the residual risk should be as low as possible, and within the organization’s risk appetite and tolerance. The information security manager should monitor and review the residual risk throughout the system development life cycle, and ensure that it is communicated and approved by the appropriate stakeholders. The other options are not the primary focus, although they may be part of the security objectives and activities. Reducing the number of vulnerabilities detected is a desirable outcome, but it does not necessarily mean that the residual risk is acceptable, as some vulnerabilities may have a higher impact or likelihood than others. Avoiding identified system threats is a preventive measure, but it does not account for unknown or emerging threats that may pose a residual risk to the system. Complying with regulatory requirements is a mandatory obligation, but it does not guarantee that the residual risk is acceptable, as regulations may not cover all aspects of security or reflect the specific context and needs of the organization.