Which statement best describes the tension in a massless, inextensible string that may pass over one or more frictionless pulleys?
a) It doubles each time the string passes over a pulley.
b) It is constant in magnitude throughout every segment of the string.
c) It decreases steadily along the string because of energy losses at each pulley.
d) It is greatest at the segment where the pulling force is applied and smallest at the far end.