Final answer:
In the context of a strategy defined under the "Retention" issue and in the "X-Sell" group, only propositions from the "X-Sell" group can be imported.
Step-by-step explanation:
In a strategy that is defined under the "Retention" issue and within the "X-Sell" group specifically, you can import propositions from the "X-Sell" group only. The system's structure often allows strategies to manage propositions within their defined groups and issues. Therefore, when working on a strategy for one specific group, such as "X-Sell," you do not have access to propositions from all groups or different issues like the Sales issue. Instead, you are limited to managing propositions that are part of the group you're currently working with.