What is the best way to transfer existing '/ip firewall filter' configuration from one router to a new system?

The most efficient way to transfer the '/ip firewall filter' configuration from one router to another is to export only this specific configuration section. By using the export command tailored to '/ip firewall filter', you generate a concise and focused output that contains only the relevant firewall filter rules. This method minimizes the risk of introducing any unrelated settings or configurations that could potentially conflict with the target router's existing setup.

Exporting just this segment of the configuration ensures that you avoid issues that may arise from transferring unnecessary configurations, such as interface settings or unrelated routing rules, which can lead to complications during restoration. In essence, this approach is straightforward and keeps the transfer process clean and efficient.

Other methods may involve additional steps or risks, such as editing backup files or inadvertently including extraneous information that could hinder proper functionality post-transfer. Thus, option A stands out as the most appropriate and streamlined solution for transferring '/ip firewall filter' configurations between routers.