To answer this question, you need to understand the events used in navigation within a list.
Option A) At user-command - This option is incorrect because the "At user-command" event is not specific to navigating from a basic list to a secondary list. It is a generic event that can be used for various user commands.
Option B) At Pfn - This option is incorrect because the "At Pfn" event is not related to navigating from a basic list to a secondary list. "Pfn" stands for "Process Function" and it is an event triggered when a specific process function is called.
Option C) At line-selection - This option is correct because the "At line-selection" event is used to navigate from a basic list to a secondary list. This event is triggered when a user selects a line in a basic list, allowing them to navigate to a more detailed view or a secondary list.
Option D) Initialization - This option is incorrect because the "Initialization" event is not specifically used for navigating from a basic list to a secondary list. The "Initialization" event is triggered when a program or application is initialized or started.
The correct answer is C) At line-selection. This option is correct because the "At line-selection" event is specifically used to navigate from a basic list to a secondary list.