What is a key feature of a client presentation mashup?

A client presentation mashup is designed to integrate various data sources and typically includes live data and AJAX functionality, enabling dynamic content updates without requiring a page refresh. This allows users to interact with the application in real-time, making for a more engaging experience. The use of AJAX facilitates seamless interaction with web services, allowing the application to fetch and display data from multiple sources or APIs dynamically.

The other options present limitations that are not aligned with the overarching capabilities of a client presentation mashup. For instance, displaying only static data would not leverage the inherent advantages of a mashup, which is meant to pull in and integrate various live datasets. Fetching data exclusively from Force.com negates the flexibility of accessing information from different platforms, a cornerstone of mashup functionality. Additionally, limiting the design to mobile applications excludes the potential for web-based implementations, further constraining the versatility that a mashup inherently offers.