Whats about C?

WAIT! I think I figured it out. Is C wrong because most of the people could disapprove of building the dam and actually support the building of roads, making the legislators proposal more acceptable?

C doesn't work because the problem with this answer choice is that we've got no reason to think that customers disapprove of the roads. The columnist definitely does, but it's possible that she's the only person who disapproves of them, so we can get rid of this choice.