Science fiction creates an appetite for interstellar space exploration among certain people.
Conclusion ("no doubt" = clearly)
One effect of science fiction has been to create an unproductive dissatisfaction with the way the world actually is.
Evidence (since)
Gaps between expectations and reality spur discontent.
Science fiction creates an appetite for interstellar space exploration, but that's not going to happen with any technology humanity will soon possess.
Evaluate
On Assumption questions, it's a very powerful habit to ask ourselves, "Is there a New Concept in the Conclusion"? Because, if so, the correct answer will usually deal with that concept.
By "New", we mean, "it was never talked about in the evidence".
This conclusion talks about "sci-fi" and talks about .
Did the evidence talk about "sci-fi"?
Yes, we have a premise saying that sci-fi creates an appetite for interstellar space exploration (which won't be satisfied anytime soon).
Did the evidence talk about ?
Certainly not in those words. But the final premise before the conclusion is talking about discontent, which is an equivalent synonym for dissatisfaction.
Is the "discontent" being talked about a discontent "with the way the world actually is"?
Sure, the premise is talking about a gap between expectation and reality. So to be discontent about that gap is to be dissatisfied with how reality measures up to our expectations.
Since there isn't a New Concept in the Conclusion, since both of them are actually talked about in the evidence, that tells us that this argument is missing a Link Between Premises.
While we don't have to formally diagram the argument, the visual might help. The conclusion represents this logic path:
Sci-fi ------------------------------> Discontent
The premises have established these two parts of that path:
appetite gap between Sci-fi --> for space expectation --> Discontent travel & reality
What we're missing is a connection from idea 2 to idea 3.
appetite gap between for space → expectation travel & reality
If you hate all that formal logic, then play Opposing Counsel and argue that,
This lawyer is arguing that it has, because gaps between expectations and reality spur discontent.
So you need to argue that, .
This lawyer will say,
So you need to argue that,
Goal
Look for an answer saying that the author assumes .