Of the bases of power, research indicates that power is most effective.

The answer would be : personal power
In the bases of power, Personal power refer to the power that came from individual capabilities. Researched showed that by having a solid personal power, a person is more likely to attain other bases of power such as social power, reward power, referent power, and coercive power, that's why it's called the most effective
 

  i think colonial period |-/