Application of Bases of Power

Application of Bases of Power
Jerri is confused. She thought that once she had the title of manager, everyone would listen to her and accept her authority and power. However, she has noticed other employees that seem to have power. Whenever someone has a question about the computer system, they always go to Helen who actually established the current system they are using. Usually Helen can get things up and running quicker than going to the support staff for help. Then there is Joe who has a remarkable amount of charm and charisma. He seems to have a power based simply upon him. Then there is Jill, her secretary, who has a power entirely of her own. Jill turns in the timecards weekly, and Jerri has seen her more than once override the time clock and clock somebody in earlier than they actually arrived or clock out for them when the employee left work early. When Jerri questioned her about it, Jill just laughed and said that they had been doing it for years and the time all averaged out. The company allowed no overtime so any extra time spent after work was not compensated. Jerri sometimes wonders if she has any power at all.
-What type of power does Joe possess?

A) reward power
B) coercive power
C) expert power
D) referent power