Logical Reasoning STEM Practice Test

The main idea here is that a sufficient-assumption statement is a missing link that, if true, makes the conclusion follow from the premises. The correct description says it completes the argument by filling gaps and making it effectively true given what's stated. Once that assumption is added, the premises alone are enough to guarantee the conclusion, so nothing else outside that link is required.

This fits because the role of such an assumption is to provide just enough extra truth to bridge the gap between what is given and what is concluded, ensuring the argument holds with certainty under those assumptions. It’s not claiming the assumption is a necessary condition in all possible worlds, nor is it something that contradicts the conclusion or is irrelevant to whether the conclusion follows.