According to Rational-Choice Theory,American Political Parties Tend to Adopt Middle-Of-The-Road

According to rational-choice theory,American political parties tend to adopt middle-of-the-road positions because

A) most Americans are centrist.
B) most Americans are conservatives,pulling both parties toward the right.
C) most Americans are extremists,holding either extremely liberal or extremely conservative views.
D) party leaders have to negotiate what is in effect a cultural war in U.S. politics.
E) party leaders have little incentive to differentiate themselves from one another.