The correct answer is B) Campaign finance laws.
The factor supporting the two-factor system that the passage describes is Campaign finance laws.
The passage mentions that the American election system doesn't really support a third party candidate running for the Presidency because that candidate can't receive public funds for his campaign. The United States law requires that a third party candidate got at least 5% of the vote in the last presidential election.
In U.S. politics, dominates the majority rule. It means that after a democratic process of having elections, the majority rules the government. In a two-party system like the one in the United States, the Republican and Democratic parties share power and government, depending on the results of an election. History has shown how difficult it is for a third party to aspire to the Presidency.
