What does the Content Builder SDK cross-document wrapper provide?

• A. A cross-document wrapper that lets your custom block's HTML page update the content block within the app in real time
• B. A REST API wrapper for server-side calls
• C. A CLI tool for deployment
• D. A data export utility

Answer: (A)

The key idea being tested is real-time, in-editor communication between a custom block and the Content Builder interface. The cross-document wrapper provides a secure bridge between your block’s HTML page (often running in an iframe) and the Content Builder editing frame, so updates you make in the block can be reflected inside the app immediately. This enables live editing and a seamless preview as you adjust content, without extra server calls. In practice, the wrapper handles the messaging flow between the block and the Content Builder UI, allowing the content block to be updated in real time as you interact with the block.

The other options describe server-side REST calls, deployment tooling, or data export utilities, which are not about enabling in-app, real-time updates between a custom block and the Content Builder editor.