Hi D,
Thanks for the question. From my perspective, I see the last sentence as clearly supporting that main conclusion:
- Conclusion: city council ought to ease restrictions on outdoor advertising
Premise: city should not place restrictions on forms of speech such as advertising.
Since the first premise already has supported the conclusion, this second premise is non-essential, which is why we classify it as an Additional Premise. The presence of the word "furthermore" helps signify that role as well.
You've interpreted that last sentence as supporting the premise used in the prior sentence. I think you did that as the two ideas can be linked, but there are two reasons that argue against that interpretation:
- *The premise in the first sentence is about the economy being in a slump; the last sentence doesn't say that we should lift restrictions in order to create revenue, but rather because you shouldn't restrict free speech. Those are dissimilar enough to suggest that the last sentence isn't being used to support the premise in the prior sentence.
*In combination with the above, the use of "furthermore" tells me the author sees this as a continuation of the argument in the prior sentence. Thus, this last sentence continues on in the vein of the prior sentence, which operated under the umbrella of the conclusion. If you think about the structure here, you have a conclusion, followed by a "because," which is then followed by "furthermore." That structure suggests that both following pieces refer back to the initial conclusion because if the last sentence was a premise for that prior premise (instead of the conclusion), there'd be a new start, or some type of reference to the slump/economic problem.
By the way, although I see this argument slightly differently than you, I like the fact that you didn't just accept the indicator as having a set meaning. you stopped to analyze it, and that's a great sign for future LSAT success. It's the little things that count, and actively analyzing words like this shows that you are paying attention to those kinds of details.
Please let me know if that helps. Thanks!