The goal of improving uptime is increasing the portion of time for which systems are operational. In Information Technology operations and service management, uptime measures availability, meaning how consistently an information system is running and accessible when users need it. High uptime is critical for business continuity, customer satisfaction, and meeting service level agreements. Improving uptime involves reducing both planned downtime, such as maintenance windows, and unplanned downtime, such as hardware failures, software crashes, network outages, or cyberattacks. Common strategies include redundancy, failover clustering, monitoring and alerting, preventative maintenance, patch management, and resilient infrastructure design. Increasing time between maintenance events can contribute indirectly, but it is not the definition of uptime improvement. Faster startup processes may reduce downtime duration during restarts, but it is only one factor. Increasing the interval between backups could actually increase risk and does not improve availability. Since uptime is fundamentally the percentage of time systems remain available and functioning, the correct objective is to increase the portion of time the systems are operational. Therefore, the correct answer is option D.