Which of these best describes 'message shortcuts'?

Message shortcuts are Slack app shortcuts specifically associated with an existing message. Slack distinguishes them from global shortcuts: global shortcuts can be initiated independently of message or channel context, whereas message shortcuts appear in an individual message's context menu and provide the app with information about that message. This makes message shortcuts particularly appropriate for operations such as creating a task from a message, escalating content, saving information to an external system, or launching a modal pre-populated with message context. Invoking the shortcut generates an interaction payload that the application processes. Message shortcuts are not keyboard-navigation commands, recurring-message schedulers, or administrator-only operations. Their distinguishing characteristic is that they provide an application action tied directly to the message selected by the user. Therefore, A is correct.