You are building an app that allows users to request changes to the Slack workspace...

Slack requires a valid trigger_id when an application opens a modal through views.open. A trigger_id is generated in response to an explicit user interaction, including a global shortcut, slash command, button interaction, or supported interactive component. This requirement ensures that an application cannot arbitrarily display modal interfaces without recent user intent. When the user invokes the “Request Changes” global shortcut, Slack sends an interaction payload to the application. The application must acknowledge that request and use the contained trigger_id when calling views.open. Slack currently specifies that a trigger_id expires approximately three seconds after it is issued, so the application must use it promptly. A response_url is used to send follow-up responses for certain interactive requests and slash commands rather than to authorize modal opening. A callback_id is an application-defined identifier used to identify interaction flows in older or specific payload contexts. The payload's verification token is likewise not a modal-opening credential. Therefore, D is correct. This is a core Design the Interactive Flow of Your App concept involving shortcuts, interaction payloads, modal invocation, and views.open.