The word "steep" (line 1 Para. 4) is closest in meaning to ______.

A．American political parties in the twentieth century.
B．The role of ideology in American politics.
C．The future direction of United States politics.
D．Difference between Republicans and Democrats.

A．They are both generally conservative.
B．Party organizations have been stronger at the state level than at the national level.
C．Party organizations have increased their influence in 1950s.
D．Democrats have been stronger than Republicans at the national level.