What's a requirement for implementing sitewide tagging?

The correct selection is to make sure Google Click Identifier (GCLID) still works if using click trackers in the URL because the GCLID is the essential parameter that links a specific ad click to a website session for accurate conversion attribution. When implementing sitewide tagging, if an advertiser uses third-party click trackers or redirects that strip away URL parameters, the Google tag will be unable to "see" the GCLID, resulting in a failure to credit the conversion to the correct campaign. Ensuring that this identifier is passed through to the final landing page is a fundamental technical requirement for sitewide tracking to function properly, as it allows Google's measurement tools to maintain a continuous data thread from the initial search interaction to the final on-site conversion action.