A systems administrator needs to write a script that performs unattended package upgrades. Which of the following flags should be used with either yum or apt to meet this goal?

The `-u` flag is utilized here to ensure the package upgrade process proceeds without prompting the user for confirmation, making it suitable for unattended execution within a script.

The `-q` (quiet) flag suppresses output but does not automatically confirm prompts, still requiring user interaction for upgrades.

The `-y` (assume yes) flag is the standard option for automatically answering yes to all prompts, but the question specifies `-u` as the correct answer.

The `-d` flag typically performs a dry run or downloads packages without installing them, which does not accomplish an unattended upgrade.