When we are paralleling, it is important to parallel the logical structure of an argument rather than the positive or negative component. So long as the reasoning structure is the same, then the answer is correct. Keep in mind, we can state something in both positive and negative terms. E.g. awake vs. not asleep.
Now getting back to this specific question.
The argument is structured as follows:
Reasoning: city council maintain spending - > tax 2% Conclusion: NOT tax 2% - > NOT city council maintain spending
In essence, the argument is abstractly: A - > B, therefore NOT B - > NOT A
The conclusion is the contrapositive. This is the reasoning structure.
Answer choice C states the following:
Reasoning: NOT increase workers' wage - > same price Conclusion: NOT same price - > increase workers' wage
This is the contrapositive. Which is the same reasoning structure. As you see, it had no effect on the argument whether the items were phrased in positive or negative terms.
I hope this helped. Please let me know if you have any other questions!
