According to the two-dimensional model of power proposed by Bachrach and Baratz, which of the following statements best describes the exercise of power?
a. The exercise of power involves both decisions and non-decisions.
b. Power is exercised when someone prevents someone from doing something they would otherwise have done.
c. Overt conflict has to be present for the exercise of power to occur.
d. Hierarchal power is the least expensive means of exerting control.