What Salesforce technology should an Integration Architect consider for securely exposing an external system's User Interface within Salesforce?

The correct answer is Canvas because it is specifically designed to securely integrate third-party applications into Salesforce. This technology enables the embedding of an external system's user interface directly into the Salesforce environment, allowing users to interact with the external system without leaving Salesforce.

Canvas provides important security features such as OAuth-based authentication and allows for the secure transmission of data between Salesforce and the external application. It also supports single sign-on (SSO), which enhances user experience by allowing users to access external apps seamlessly while remaining authenticated within Salesforce.

This makes it an optimal choice for Integration Architects looking to expose external user interfaces while maintaining robust security protocols. Other options like Visualforce and Lightning Components are more focused on creating interfaces and components within Salesforce, rather than integrating and showcasing external systems directly. Custom Web Tabs are generally used for adding web content within Salesforce but lack the comprehensive security and integration features that Canvas provides.