How Did the Development of Towns Drive the Evolution of Medieval

How did the development of towns drive the evolution of medieval society?

A) Towns made possible a class of free people,able to travel and choose their occupation.
B) By reducing the number of laborers raising food,towns made life on isolated farms more difficult.
C) Towns gave merchants a place to meet and trade,which they had lacked before towns emerged.
D) By concentrating more people in fortified towns,wars between European states became more difficult to wage.
E) The tendency of serfs to flee into towns made lords hostile to such cultures,increasing internal tensions.