Max Weber Likened the History of Society to a Train

Max Weber likened the history of society to a train and ideas to the switchmen of the tracks.What does this mean?

A) Ideas can be powerful forces to create change and alter the course of history when enough people believe them at the right time.
B) Ideas control the actions of people and can stop the progress of society.
C) Ideas control the materialistic human urge to hoard wealth,much like a train will speed out of control if not slowed down.
D) Ideas control the basic human urge toward individualism by keeping people in the same society moving down the same track together.