This is actually a "Must Be True" question. It is asking us to accept everything in the passage as fact. Note that it says "if true" in the question stem. Then we choose an answer that is supported by those facts. We do not evaluate the strength of an argument, nor do we add new information to it.
A strengthen with sufficient question stem will be something like this: "The conclusion is properly drawn if which of the following is assumed?" This question type is asking us to choose new information that will make the conclusion valid. Take a look under the "Strengthen" video lesson for explanations of strengthen w/ sufficient and strengthen w/ necessary.
TimBMarch 14, 2020
Thank you! I appreciate the response
RaviMarch 15, 2020
@TimB, let us know if you have any other questions!
