by joshringu Fri Jul 19, 2013 4:57 pm
Hi!
I know I am a year late, but to answer your question for (C). I think it is incorrect because it is not a necessary assumption. Financial incentives could have a significant effect on productivity, but it won't destroy the argument. Because it is possible that financial incentives has a significant effect, but also more supervision could at the same time have a significant effect. Both are just one way to solve the issue.
If you negate it, it does not destroy the argument.
Hope that helped or helps any future on-lookers here!