Strenghten with sufficient?

Hi Claudia, thanks for the question. You're totally right to notice that it includes a phrase commonly used in the "strengthen with sufficient premise" questions. (I.e. properly drawn). However, we should note that the question stem is saying that the argument "has" to assume this in order for it to be properly drawn. Considering the necessity of the assumption, we can deduce that this question is strengthen with necessary premise. How to differentiate these questions is by noticing the usage of necessary or sufficient indicators in the question stem. The strengthen with sufficient questions will use words like "if", "when", etc. The strengthen with necessary questions will use words like "requires", "have to", "must", etc. I hope this helps. Please let me know if you have any other questions!