ylee57: (E) just says that all the buyers of these bonds (the above-average interest rate bonds) will receive the same rate per bond. Thus it still stands that people will be more willing to buy these bonds (since they're at a higher interest rate), and this doesn't weaken the conclusion.
IndigoIntentions: Your explanation of (A) makes a lot of sense, but I think your explanation of (B) is off. Like you said, the assumption is that the answer choices are true, so you can't go into depth trying to figure out whether income tax revenues would increase or wouldn't... the answer choice says that they would decrease.
Looking at the question some more, I think I found my error.
Evidence 1: Hospitals are suffering from a lack of money for expansion
Evidence 2: More money for gov't from municipal bonds leads to more money available for hospitals' expansion projects
Assumption: increasing municipal bond interest rates leads to more bond sales
Conclusion: Local gov't should sell above average rate municipal bonds
I mistook Evidence 2 for the conclusion, but because it's stated as evidence, it's a straight up truth. Therefore, even if the local gov't has a huge loss in revenue from income taxes, it doesn't effect the argument. I went outside the argument and figured that the local gov't was working from one big bucket of money, but if municipal bond revenues are kept in a separate bucket, then the argument still stands unaffected.
Tough question! Thanks for the feedback everyone. And thanks to Jen from Knewton for the CR2 Knewton class that helped me make sense of this question.