Succeed Insurance needs to modify an existing PolicyCenter typelist called PreferredContactMethod with new options.

Guidewire uses a specific file naming convention to separate base product definitions from customer extensions. ForTypelists(which are essentially enums stored in the database), the base definition is stored in a .tti (Typelist Interface) file.

According toCloud Delivery Standards, you never modify the base .tti file (Option D). Instead, to add new codes to an existing typelist, you create aTypelist Extensionfile with the.ttxsuffix (Option A). The file name must exactly match the base typelist name. Options B and C are incorrect because the _Ext suffix is required fornewentities or typelists, but forextendingan existing Guidewire typelist, the .ttx suffix is the standard mechanism that ensures the new codes are merged correctly with the original ones during a platform upgrade.