What command is used to change the log level of the agent without restarting it?

The command that allows you to change the log level of the Datadog agent without requiring a restart is accurately represented by the choice that includes "agent config set log_level debug." This command allows you to specify the new log level directly, in this case, setting it to "debug."

Using this command provides the flexibility to adjust logging verbosity dynamically, which can be particularly useful for troubleshooting and monitoring purposes. It ensures that the agent can immediately start logging information at the specified level without needing to go through a restart process, thus maintaining the continuity of monitoring and performance tracking.

The other options might seem plausible at first glance, but they do not convey the correct syntax or the required functionality. For example, commands that do not handle the configuration structure appropriately or lack the necessary parameters would not achieve the intended result of changing the log level in an efficient manner.