The primary purpose of an Appian interface object is to create the user interface (UI) through which end users interact with the application. Interfaces are used to build all user-facing components, such as forms for data entry, reports for data visualization, and dashboards for displaying key information. They are the fundamental building blocks for creating an engaging and functional user experience, allowing users to view, input, and manipulate application data.

A. This describes the function of an Integration object, which is used to call external systems and APIs.

C. This is handled by objects like record types, query rules, and data store smart services, not directly by the interface object itself.

1. Appian Documentation, "Interface Object": "Interfaces are the primary way that your users will interact with your applications. Every form, dashboard, and landing page is an interface. You'll design, build, and test all of your interfaces in the interface object." (Appian 23.4, Design Objects > Interface Object)

2. Appian Documentation, "Integration Object": "Integration objects are used to call external systems (web services, APIs) from Appian. Integrations can be used to either retrieve data from other systems or to send data to them." (Appian 23.4, Design Objects > Integration Object)

3. Appian Documentation, "Record Type Object": "The record type is a powerful design object that allows you to connect your business data to your Appian applications... you can easily connect to your enterprise data in a database, Salesforce, or other web service..." (Appian 23.4, Design Objects > Record Type Object)