One Reason That Political Parties in the United States Today

One reason that political parties in the United States today are weaker than those in Europe is that in the United States,

A) party leaders do not typically select people to run for office.
B) local party leaders rarely have as much power as national ones.
C) political party organizations are highly centralized.
D) Congress reserves the right to select the chief executive of the government.
E) party leaders have become less ideological.