@victoriac Thanks for your question. The question stem is only way to distinguish between Strengthen with Necessary Premise questions and Strengthen with Sufficient Premise questions.
In Strengthen with Necessary question stems you will encounter necessary terminology (e.g., only, only if, unless, must, presupposes, depends, etc.).
In Strengthen with Sufficient question stems you will notice sufficient terminology (e.g., if). Beyond that however, remember that Strengthen with Sufficient are asking you to 100% guarantee the conclusion so you will notice the following terminology: properly concluded, follows logically, properly drawn, etc.
So let's take a look at a few examples to clarify:
Example #1: Which one of the following is an assumption on which the explanation above depends?
The word "depends" lets us know that this is a Strengthen with Necessary question.
Example #2: Which one of the following is an assumption that would permit the conclusion above to be properly drawn?
Here, the language "permit the conclusion above to be properly drawn" tells us that this is a Strengthen with Sufficient question.
Please note that both examples include the word "assumption" so we cannot distinguish based on that. This makes sense since both Strengthen w/ Necessary & Strengthen w/ Sufficient have unstated premises (i.e. assumptions) that we are trying to identify.
Hope this helps! Please let us know if you have any other questions.
