Which method uses automation to increase efficiency and project schedule flexibility in IT operations?

The correct choice is Continuous Integrity/Continuous Delivery. This method focuses on integrating automated processes in software development and IT operations, which significantly enhance efficiency and promote flexibility in project schedules. Continuous Delivery involves automatically preparing code changes for release to production, allowing teams to deliver features, fixes, or updates rapidly while minimizing risk and downtime.

Automation reduces the manual effort typically required in deployment processes and testing, streamlining operations and enabling quicker response times to changes or issues that may arise. This agility is beneficial in modern IT environments where adjustments to project scope and timelines are common.

The other options, while relevant to IT operations in various aspects, do not specifically target the automation of project efficiency and scheduling flexibility in the same comprehensive way as Continuous Integrity/Continuous Delivery does. Cloud change control and on-premises change control imply managing changes in specific environments but do not inherently address the automation aspect to the extent necessary for increasing operational efficiency and scheduling flexibility. Tiered architecture, although important for design and scalability, primarily relates to the structural organization of IT systems rather than automation itself.