D. System upgrade

Explanation:
The answer is “D. System upgrade” because it is not a direct metric of information system success. Success is typically measured by system efficiency, effectiveness, performance, and usability, while a system upgrade refers to the process of improving or updating the system, not a success metric.

Run-down of reasoning:

• System success is measured by how well it performs in terms of efficiency, effectiveness, and usability. A system upgrade is a process, not a metric for evaluating success.