Answer:
D but if you think its C, take it.
Explanation:
As a Canadian looking in on this question, things that appear negative to most Americans is somewhat of a positive for me.
A is not answering the question. If they have no money and no affect on elections then the major parties can just swat them away as they would a fly.
B: This is true of third party candidates although why it is true is beyond me. A third party (see your other question about Ralph Nader and Ross Perot) often see things that the major two don't want to see. And the Democrats and Republicans have the money to squash the good intentions of a third party. And the voters believe them. To vote for a third party is to waste a vote. I've heard that more than once.
C: They can and they do. What's the problem? If the third party exerts that much pressure, maybe we ought to listen.
D: I honestly don't know about D. I would say that it is likely true, although never is a pretty strong word. So I'll pick it, but I think C is perhaps intended as the answer. I see it as a virtue. If you can think of a reason for choosing C, then do it.